JP2004349600A - Oxide semiconductor light emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ZnO system oxide semiconductor light emitting element which has a small oscillation threshold current and is excellent in reliability. <P>SOLUTION: An n-type buffer layer 102, an n-type clad layer 103, an n-type optical guide layer 104, a nondoped quantum well layer 105, a p-type optical guide layer 106 and a p-type clad layer 107 are laminated one by one on an n-type ZnO single crystalline substrate 101. The p-type optical guide layer 106 consists of a lower layer of a 10 nm-thick Cd<SB>0.05</SB>Zn<SB>0.95</SB>O layer 106a, an intermediate layer of a 10 nm-thick Cd<SB>x</SB>Zn<SB>1-x</SB>O layer 106b (wherein x changes from 0.05 to 0 continuously) and an upper layer of a 10 nm-thick Mg<SB>y</SB>Zn<SB>1-y</SB>O layer 106c (wherein y changes from 0 to 0.1 continuously). The band gap energy of the p-type optical guide layer 106 tilts to be large as it gets close to the p-type clad layer 107 side from the nondoped quantum well layer 105. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an oxide semiconductor light emitting device such as an oxide semiconductor laser and a method of manufacturing the oxide semiconductor light emitting device, and more particularly, to an oxide semiconductor light emitting device such as an oxide semiconductor laser having a low oscillation threshold current and excellent reliability. And a method for manufacturing the oxide semiconductor light emitting device.
[0002]
[Prior art]
In an oxide semiconductor light emitting device such as a semiconductor laser using an oxide semiconductor, a separated confinement heterostructure in which a light guide layer is formed between an active layer and a cladding layer is often used. In a semiconductor laser device to which this separated confinement heterostructure is applied, the light confinement rate in the active layer is improved by the light guide layer, and it is extremely effective in reducing the oscillation threshold current and controlling the waveguide mode.
[0003]
As a semiconductor laser device to which the separated confinement heterostructure is applied, for example, there is one disclosed in Japanese Patent No. 3235440 (Patent Document 1). This semiconductor laser device is a group III nitride-based semiconductor light emitting device that emits light having a wavelength in the blue to ultraviolet region, and a group III nitride-based semiconductor layer containing Al, a GaN layer, And a group III nitride-based semiconductor layer (only an n-type guide layer) containing the same is laminated to form an optical guide layer.
[0004]
As another oxide semiconductor light-emitting element, there is an element using zinc oxide (ZnO). Zinc oxide (ZnO) is a direct transition type semiconductor having a band gap energy of about 3.4 eV, has an extremely high exciton binding energy of 60 meV, is inexpensive in raw materials, is harmless to the environment and the human body, and has a simple film forming method. There is a possibility that a light emitting device having high efficiency, low power consumption, and excellent environmental performance can be realized.
[0005]
An oxide semiconductor light-emitting device using a ZnO-based semiconductor including ZnO and a mixed crystal represented by MgZnO or CdZnO based on the same is disclosed in, for example, International Publication WO00 / 16411 (Patent Document 2). There are things. This oxide semiconductor light emitting device has a double hetero structure using a CdZnO quantum well active layer, and has an optical guide layer provided between a stress relaxation layer and a cladding layer.
[0006]
[Patent Document 1]
Japanese Patent No. 3235440
[Patent Document 2]
International Publication WO00 / 16411
[0007]
[Problems to be solved by the invention]
However, there has been no semiconductor laser device having a small oscillation threshold current utilizing a large free exciton binding energy, which is a feature of a ZnO-based semiconductor.
[0008]
For example, the present inventor has previously prepared a ZnO-based semiconductor by forming a quantum well active layer having a large optical gain and forming an optical guide layer around the quantum well active layer in order to reduce the oscillation threshold current. Although a laser device was manufactured, the ZnO-based semiconductor laser device manufactured in this manner had problems that the oscillation threshold current was not significantly reduced and the device life was extremely short.
[0009]
Accordingly, an object of the present invention is to provide a ZnO-based oxide semiconductor light emitting device having a small oscillation threshold current and excellent reliability.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, an oxide semiconductor light emitting device according to the present invention includes a first conductive type clad layer, a first conductive type light guide layer, an active layer, and a second conductive layer formed of at least a ZnO-based semiconductor above a substrate. A conductive type light guide layer and a second conductive type clad layer are stacked in this order, and the band gap energy of the second conductive type light guide layer is equal to or greater than the band gap energy of the active layer, and The band gap energy is equal to or less than the band gap energy of the cladding layer, and the band gap energy of the second conductivity type light guide layer is inclined so as to increase from the active layer side to the second conductivity type cladding layer side. It is characterized by:
[0011]
In this specification, the ZnO-based semiconductor is defined as a semiconductor made of only ZnO crystal or a semiconductor obtained by mixing ZnO crystal such as MgZnO or CdZnO semiconductor having the same as a host.
[0012]
In this specification, the first conductivity type refers to n-type or p-type. When the first conductivity type is n-type, the second conductivity type is p-type. When the first conductivity type is p-type, the second conductivity type is n-type.
[0013]
The expression “at least the bandgap energy of the active layer” means, for example, that the second conductive type light guide layer may be formed when the second conductive type light guide layer has a superlattice structure. , The band gap energy of the active layer partially becomes smaller than the band gap energy of the active layer in the vicinity of the active layer.
[0014]
In addition, the expression “increases from the active layer side to the second conductive type cladding layer side” means that the band gap energy is partially constant from the active layer side to the second conductive type cladding layer side. Or the band gap energy is locally increased from the active layer side to the second conductive type clad layer side, as may occur when the structure of the second conductive type light guide layer is a super lattice structure. Is included.
[0015]
The inventor can reduce the oscillation threshold current of the oxide semiconductor light emitting device and improve the reliability of the oxide semiconductor light emitting device by making the band gap energy of the light guide layer of the oxide semiconductor light emitting device inclined. I found that I can do it. That is, the present inventor has reported that the ZnO-based semiconductor has a property that the refractive index decreases as the bandgap energy increases, and that the bandgap energy has a composition ratio of Zn and Cd or Zn and Mg, which are Group II elements. By paying attention to what is determined by the above, if the composition ratio of Zn and Cd or Zn and Mg is changed appropriately and the composition of the light guide layer is appropriately inclined, the light guide layer is formed with a constant composition. It has been found that the light confinement effect can be made larger than in the case and the oscillation threshold current can be reduced. In particular, the present inventor has found that the bandgap energy on the side of the second conductivity type light guide layer is inclined so as to increase from the active layer side to the side of the second conductivity type clad layer. It has been found that the crystal defects can be reduced, the operation can be performed with a low current, and the reliability can be increased, as compared with the case where the conditions are sharply changed.
[0016]
According to the oxide semiconductor light emitting device of the present invention, the bandgap energy of the light guide layer of the second conductivity type is inclined so as to increase from the active layer side to the cladding layer side of the second conductivity type. Therefore, the oxide semiconductor light-emitting element can operate with a low current, and the reliability of the oxide semiconductor light-emitting element can be increased.
[0017]
In one embodiment, the bandgap energy of the first conductivity type light guide layer is equal to or greater than the bandgap energy of the active layer, and the bandgap energy of the first conductivity type cladding layer is one. The band gap energy of the first conductivity type light guide layer is characterized in that it is inclined so as to increase from the active layer side to the first conductivity type clad layer side.
[0018]
The expression “above the band gap energy of the active layer” refers to, for example, the first conductive type light guide layer, which can occur when the structure of the first conductive type light guide layer is a super lattice structure. , The band gap energy of the active layer partially becomes smaller than the band gap energy of the active layer in the vicinity of the active layer.
[0019]
In addition, the expression “increases from the active layer side to the first conductive type clad layer side” means that the band gap energy is partially constant from the active layer side to the first conductive type clad layer side. Or the bandgap energy is locally increased from the active layer side to the first conductive type clad layer side, as may occur when the first conductive type light guide layer has a superlattice structure, for example. Is included.
[0020]
According to the above embodiment, the composition of the first conductivity type light guide layer is also graded in addition to the composition of the second conductivity type light guide layer being graded, so that the light confinement ratio can be further improved. . Also, by inclining the composition of the first conductivity type light guide layer, the light intensity distribution becomes symmetrical, so that the stability of single mode oscillation can be improved. In addition, since the change in conditions during the growth of the first conductivity type light guide layer is reduced, crystal defects can be further reduced. Accordingly, the oxide semiconductor light-emitting element can have excellent optical characteristics and high reliability.
[0021]
In one embodiment, at least one of the first conductivity type light guide layer and the second conductivity type light guide layer has a stacked structure in which two or more layers having different compositions are stacked. It is characterized by having.
[0022]
According to the above embodiment, since the light guide layer has a laminated structure of two or more layers having different compositions, the refractive index and the band gap energy, which are difficult to control only by inclining the composition ratio, lead to minute changes. Can be completely controlled. Further, for example, by selecting a MgZnO mixed crystal layer having a large band gap energy as one layer of a laminated structure, carrier confinement in an active layer can be improved, and an oxide semiconductor light emitting element has excellent optical characteristics. Can be
[0023]
In one embodiment, the oxide semiconductor light-emitting element is characterized in that the stacked structure includes a superlattice structure of ZnO-based semiconductors having different compositions.
[0024]
According to the above embodiment, since the structure of the light guide layer is a superlattice structure of ZnO-based semiconductors having different compositions, the change in the refractive index and the band gap energy can be more finely controlled, and the carrier mobility can be improved. . Therefore, the oxide semiconductor light-emitting element can have excellent electric characteristics and optical characteristics.
[0025]
In one embodiment, the inclined band gap energy of at least one of the first conductivity type light guide layer and the second conductivity type light guide layer varies stepwise in a discontinuous manner. It is characterized by doing.
[0026]
According to the above embodiment, the composition ratio is changed stepwise by changing the growth condition of at least one of the first conductivity type light guide layer and the second conductivity type light guide layer discontinuously stepwise. In addition, it is possible to use a crystal growth technique such as a laser molecular beam epitaxy method in which continuous changes in conditions are difficult, and it is possible to easily tilt the composition by using a laser molecular beam epitaxy method or the like. From this, a growth method suitable for the oxide crystal can be selected according to the situation, so that the emission characteristics of the oxide semiconductor light-emitting element can be improved and the reliability of the oxide semiconductor light-emitting element can be increased.
[0027]
In one embodiment, the oxide semiconductor light emitting device is not inclined so that the bandgap energy of the first conductive type light guide layer increases from the active layer side toward the first conductive type clad layer side. in case of,
A second conductivity type carrier having a larger band gap energy than the second conductivity type light guide layer and the second conductivity type cladding layer between the second conductivity type light guide layer and the second conductivity type cladding layer; Forming an overflow suppression layer,
When the bandgap energy of the first conductivity type light guide layer is increased so as to increase from the active layer side to the first conductivity type clad layer side,
A second conductivity type carrier having a larger band gap energy than the second conductivity type light guide layer and the second conductivity type cladding layer between the second conductivity type light guide layer and the second conductivity type cladding layer; With overflow suppression layer
A first conductive type having a band gap energy larger than that of the first conductive type light guide layer and the first conductive type clad layer between the first conductive type light guide layer and the first conductive type clad layer. At least one of the carrier overflow suppressing layers is formed.
[0028]
According to the above-described embodiment, a band gap energy between the second conductive type light guide layer and the second conductive type clad layer, which is larger than that of the second conductive type light guide layer and the second conductive type clad layer. The first conductivity type light guide layer and the first conductivity type clad layer between the second conductivity type carrier overflow suppression layer having the following, the first conductivity type light guide layer, and the first conductivity type clad layer. Since at least one of the first conductivity type carrier overflow suppression layers having a larger band gap energy is formed, carrier overflow from the active layer can be suppressed, and the luminous efficiency of the oxide semiconductor light emitting element can be improved.
[0029]
In one embodiment, the oxide semiconductor light emitting device is characterized in that the active layer has a quantum well structure.
[0030]
The quantum well active layer has advantages such as excellent polarization selectivity and high optical gain and characteristic temperature.If the active layer has a quantum well structure, a high performance semiconductor laser device can be manufactured. In addition, there is a disadvantage that the light confinement ratio is small due to the thin active layer. In the present invention, the bandgap energy of the light guide layer is increased from the active layer side to the clad layer side, so that the refractive index of the light guide layer can be increased on the active layer side and reduced on the clad layer side, and the active layer can be activated. The light confinement of the layer can be increased. Therefore, when the active layer has a quantum well structure, the emission characteristics of the oxide semiconductor light-emitting element can be further improved.
[0031]
The method of manufacturing an oxide semiconductor light-emitting device according to the present invention may further include a first conductive type clad layer, a first conductive type light guide layer, an active layer, and a second conductive type formed at least above the substrate. A method for manufacturing an oxide semiconductor light emitting device, wherein the light guide layer and the second conductivity type clad layer are manufactured in this order, wherein the oxide semiconductor light emitting device is stacked.
A layer made of a ZnO-based semiconductor containing at least a portion of Cd in at least one of the second conductivity type light guide layer and the first conductivity type light guide layer is provided at a constant supply rate of Cd and Zn and at a growth temperature. By changing the ratio of Cd to Zn in at least a part of the light guide layer in a direction substantially perpendicular to the substrate, the second conductive type light guide layer and the first conductive type light guide layer A step of inclining at least one band gap energy,
A layer made of a ZnO-based semiconductor containing at least a portion of Mg in at least one of the second conductivity type light guide layer and the first conductivity type light guide layer is provided at a constant Zn and Mg supply rate and at a growth temperature. By changing the ratio of Mg to Zn in at least a part of the light guide layer in a direction substantially perpendicular to the substrate, the second conductive type light guide layer and the first conductive type light guide layer A step of inclining at least one band gap energy
Is characterized in that at least one of the steps is provided.
[0032]
Since Cd has a higher vapor pressure than Zn, when the growth temperature increases, the Cd composition ratio to Zn decreases even when the supply rate is constant. Since Mg has a lower vapor pressure than Zn, when the growth temperature is increased, the Mg composition ratio with respect to Zn increases even if the supply rate is constant. Therefore, by controlling only the growth temperature, the Cd composition ratio to Zn or the Mg composition ratio to Zn can be easily changed, and the band gap energy can be inclined. The number of steps can be reduced, and the productivity of the oxide semiconductor light-emitting element can be improved.
[0033]
The method of manufacturing an oxide semiconductor light-emitting device according to the present invention may further include a first conductive type clad layer, a first conductive type light guide layer, an active layer, and a second conductive type formed at least above the substrate. A method for manufacturing an oxide semiconductor light emitting device, wherein the light guide layer and the second conductivity type clad layer are manufactured in this order, wherein the oxide semiconductor light emitting device is stacked.
A layer made of a ZnO-based semiconductor containing at least a portion of Cd in the second conductivity type light guide layer is grown on the substrate by reducing the supply rate of Cd and changing the growth temperature. Changing the ratio of Cd to Zn in at least a portion of the light guide layer in a vertical direction to incline the bandgap energy of the light guide layer of the second conductivity type; By growing the layer made of the ZnO-based semiconductor including the Cd supply rate and increasing the growth temperature, the ratio of Cd to Zn in at least a portion of the Zn in a direction substantially perpendicular to the substrate. And inclining the bandgap energy of the light guide layer of the first conductivity type. And the extent,
By growing a layer made of a ZnO-based semiconductor containing at least a part of Mg in the second conductivity type light guide layer under the condition of increasing the supply rate of Mg and changing the growth temperature, the layer is substantially formed on the substrate. Changing the ratio of Mg to Zn in the at least one portion in a vertical direction to incline the bandgap energy of the light guide layer of the second conductivity type; and removing at least a portion of the Mg in the light guide layer of the first conductivity type. By growing a layer comprising a ZnO-based semiconductor containing Mg under a condition in which the supply rate of Mg is reduced and the growth temperature is changed, the ratio of Mg to Zn in at least a portion of the Zn in a direction substantially perpendicular to the substrate. And inclining the bandgap energy of the light guide layer of the first conductivity type. And the extent
Wherein at least one of the steps is provided.
[0034]
Note that the expression “reduce (or increase) the supply speed of Cd” or “reduce (or increase) the supply speed of Mg” indicates that the supply speed of Cd is partially (not entirely). ), Or the case where the supply rate of Mg is partially (but not entirely) constant.
[0035]
When the supply rate of Cd or Mg is reduced (or increased) as in the above invention, the controllability of the band gap energy gradient can be further improved, and an oxide semiconductor light emitting element having excellent optical characteristics can be manufactured.
[0036]
In one embodiment, the method for manufacturing an oxide semiconductor light-emitting device includes a step of setting a growth temperature when growing at least one of the layer made of the ZnO-based semiconductor containing Cd and the layer made of the ZnO-based semiconductor containing Mg. It is characterized by being continuously changed.
[0037]
When the growth conditions are continuously changed and the composition ratio is continuously inclined as in the above embodiment, crystal defects can be reduced as compared with the case where the growth conditions are sharply changed. The reliability of the element can be increased.
[0038]
In one embodiment, the method for manufacturing an oxide semiconductor light-emitting element includes a step of adjusting a growth temperature when growing at least one of the layer made of the ZnO-based semiconductor containing Cd and the layer made of the ZnO-based semiconductor containing Mg. It is characterized in that it is changed stepwise.
[0039]
According to the above embodiment, the growth conditions are changed by changing the growth temperature stepwise, so that the band gap energy can be easily adjusted by using a crystal growth technique in which continuous changes in conditions such as a laser molecular beam epitaxy method are difficult. It can be tilted, and crystal defects can be reduced as compared with the case where the growth conditions are sharply changed. Accordingly, the oxide semiconductor light-emitting element can have excellent optical characteristics and reliability.
[0040]
In one embodiment, the method for manufacturing an oxide semiconductor light emitting device is characterized in that the supply speed of at least one of Cd and Mg is changed stepwise.
[0041]
When the supply rate of Cd or Mg is changed stepwise as in the above embodiment, the change in the growth condition is further alleviated, and the crystal defects are further reduced. Thus, the reliability of the oxide semiconductor light-emitting element can be further improved.
[0042]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0043]
(1st Embodiment)
FIG. 1 is a structural perspective view and a band profile near an active layer of a ZnO-based semiconductor laser device which is an oxide semiconductor light emitting device according to a first embodiment of the present invention.
[0044]
This semiconductor laser device is formed on an n-type ZnO single crystal substrate 101 having a zinc surface as a main surface as an example of a semiconductor substrate (in the first embodiment, the first conductivity type is n-type and the second conductivity type is p-type). And the Ga doping concentration is 1 × 10¹⁸cm^{− 3}N-type ZnO buffer layer 102 having a thickness of 0.1 μm and a Ga doping concentration of 3 × 10¹⁸cm^{− 3}N-type Mg with a thickness of 1 μm_{0 . 1}Zn_{0 . 9}O cladding layer 103, Ga doping concentration of 5 × 10¹⁷cm^{− 3}N-type Cd with thickness of 30 nm_{0 . 05}Zn_{0 . 95}O light guide layer 104, non-doped quantum well active layer 105 as an example of active layer, N doping concentration of 1 × 10¹⁸cm^{− 3}P-type light guide layer 106 having a thickness of 30 nm and an N doping concentration of 5 × 10¹⁹cm^{− 3}1.2 μm thick p-type Mg_{0 . 1}Zn_{0 . 9}O cladding layer 107, N doping concentration is 1 × 10²⁰cm^{− 3}And a 0.5 μm-thick p-type ZnO contact layer 108 is sequentially laminated.
[0045]
The non-doped quantum well active layer 105 has a thickness of 5 nm._{0 . 05}Zn_{0 . 95}Two O barrier layers and 6 nm thick Cd_{0 . 1}Zn_{0 . 9}It is formed by alternately laminating three O well layers alternately. In FIG. 1, an arrow A indicates a direction in which the band gap energy increases, and a curve B indicates the band gap energy of each layer. As shown in FIG._{0 . 05}Zn_{0 . 95}The band gap energy of the two O barrier layers is Cd_{0 . 1}Zn_{0 . 9}It is larger than the band gap energy of the three O well layers, and electrons and holes are converted to Cd._{0 . 1}Zn_{0 . 9}The three O-well layers can be confined mainly.
[0046]
The p-type light guide layer 106 is made of Cd having a thickness of 10 nm._{0 . 05}Zn_{0 . 95}O layer 106a, 10 nm thick Cd_xZn_{1 − x}O layer 106b and 10 nm thick Mg_yZn_{1 − y}It is composed of three layers of the O layer 106c. The Cd composition ratio x continuously changes from 0.05 to 0, and the Mg composition ratio y continuously changes from 0 to 0.1. As described above, by continuously changing the Cd composition and the Mg composition ratio, as shown in FIG. 1, the semiconductor laser device of this embodiment has a structure in which the band gap energy of the p-type P-type Mg from the well active layer 105 side_{0 . 1}Zn_{0 . 9}It is inclined so as to increase toward the O-clad layer 107. In this embodiment, the Cd_{0 . 05}Zn_{0 . 95}The band gap energy of the two O barrier layers and Cd as the first optical guide layer_{0 . 05}Zn_{0 . 95}The band gap energy of the O layer 106a is set to the same value, and the energy depth of the quantum well is the same on both sides of the quantum well.
[0047]
The p-type ZnO contact layer 108 and the p-type MgZnO cladding layer 107 are etched into a ridge stripe shape.¹⁸cm^{− 3}-Type Mg doped at a concentration of_{0 . 2}Zn_{0 . 8}The O current block layer 109 is embedded.
[0048]
Under the ZnO substrate 101, an n-type ohmic electrode 110 is formed, while a p-type ZnO contact layer 108 and an n-type Mg_{0 . 2}Zn_{0 . 8}On the O current block layer 109, a p-type ohmic electrode 111 is formed.
[0049]
The semiconductor laser device of the first embodiment is manufactured by a molecular beam epitaxy (hereinafter, referred to as MBE) apparatus shown in FIG.
[0050]
In this MBE apparatus, a substrate holder 202 is disposed above a growth chamber 201 that can be evacuated to an ultra-high vacuum, and a substrate 203 is fixed to the substrate holder 202. The substrate holder 202 is heated by a heater 204 disposed above the substrate holder 202, and the substrate 203 is heated by the heat conduction. Immediately below the substrate holder 202, a plurality of evaporation cells 205 filled with a semiconductor material are arranged at an appropriate distance. Each of the evaporation cells 205 is heated by a heater 206 provided on the side surface, and the evaporated molecular material is deposited on the substrate 203 to grow a thin film. Each evaporation cell 205 has a shutter 207. The MBE apparatus stacks thin films having different compositions by controlling opening and closing of the shutter 207 of each evaporation cell 205. Further, a radical cell 208 is provided in the growth chamber so that a plasma-like gas source can be introduced.
[0051]
Hereinafter, a method for manufacturing the semiconductor laser device of the first embodiment will be described mainly with reference to FIGS.
[0052]
First, the cleaned ZnO substrate 101 is introduced into an MBE apparatus, and is heated at a temperature of 600 ° C. for 30 minutes to be cleaned. After that, the substrate temperature is lowered to 450 ° C. and an oxygen radical cell, a Zn cell, and a Ga cell are removed. The shutter is opened, and the n-type ZnO buffer layer 102 is grown. At this time, the Ga doping concentration is controlled by the Ga molecular beam intensity on the substrate.
[0053]
Next, the substrate temperature was raised to 500 ° C., and the shutters of the oxygen radical cell, the Zn cell, the Mg cell, and the Ga cell were opened, and the Ga-doped n-type Mg was removed._{0 . 1}Zn_{0 . 9}After growing the O-cladding layer 103, the substrate temperature is lowered to 425 ° C., and the shutters of the oxygen radical cell, Zn cell, Cd cell and Ga cell are opened, and Ga-doped n-type Cd_{0 . 05}Zn_{0 . 95}The O light guide layer 104 is grown.
[0054]
Next, the temperature of the substrate was lowered to 400 ° C., and the opening and closing of the shutters of the oxygen radical cell, the Zn cell, and the Cd cell were controlled._{0 . 05}Zn_{0 . 95}O barrier layer and Cd_{0 . 1}Zn_{0 . 9}O-well layers are alternately stacked to grow the non-doped quantum well active layer 105.
[0055]
Next, the light guide layer 106 is formed. First, the substrate temperature was raised to 425 ° C., and the shutters of the nitrogen radical cell, oxygen radical cell, Zn cell and Cd cell were opened, and nitrogen-doped p-type Cd_{0 . 05}Zn_{0 . 95}After growing the O light guide layer 106a, the molecular beam intensity of each raw material is kept constant, and the temperature is gradually increased from 425 ° C. to 450 ° C. while the Cd composition ratio x is continuously from 0.05 to 0. Graded nitrogen doped Cd_xZn_{1 − x}The O light guide layer 106b is grown. Thereafter, the shutters of the nitrogen radical cell, oxygen radical cell, Zn cell, and Mg cell are opened, the molecular beam intensity of each raw material is kept constant, and the temperature is gradually increased from 450 ° C to 500 ° C. Mg doped with nitrogen having a ratio y continuously sloping from 0 to 0.1_yZn_{1 − y}The O light guide layer 106c is grown.
[0056]
Next, the substrate temperature and the molecular beam intensity of each raw material were kept constant, and p-type Mg_{0 . 1}Zn_{0 . 9}After growing the O-cladding layer 107, the substrate temperature is lowered to 450 ° C., and the shutters of the nitrogen radical cell, oxygen radical cell, and Zn cell are opened to grow the p-type ZnO contact layer 108 doped with nitrogen. .
[0057]
Thereafter, the substrate 101 is taken out from the MBE apparatus, and the p-type ZnO contact layer 108 and the p-type Mg_{0 . 1}Zn_{0 . 9}After etching the upper part of the O-cladding layer 107 into a ridge shape having a width of about 1.5 μm, the substrate 101 is introduced again into the MBE apparatus, the substrate temperature is raised to 550 ° C., and oxygen radical cells, Zn cells, Opening the shutters of the Mg cell and the Ga cell, and n-type Mg doped with Ga so as to contact the ridge beside the ridge._{0 . 2}Zn_{0 . 8}The O current blocking layer 109 is grown. Thereafter, the substrate 101 is taken out of the MBE apparatus, and the n-type Mg deposited on the ridge stripe is removed._{0 . 2}Zn_{0 . 8}The p-type ZnO contact layer 108 is exposed by removing the O layer by etching.
[0058]
Finally, the p-type ZnO contact layer 108 and the n-type Mg_{0 . 2}Zn_{0 . 8}100 nm thick Ni as the p-type ohmic electrode 111 is vacuum-deposited on the entire upper surface of the O current block layer 109, and 100 nm thick Al as the n-type ohmic electrode 110 is vacuum-deposited on the entire back surface of the ZnO substrate 101. The main part of the semiconductor laser device of the first embodiment is manufactured by vapor deposition.
[0059]
After manufacturing the main part of the semiconductor laser of the first embodiment, the ZnO substrate 101 is cleaved to generate a bar, and an end face mirror is formed on the end face of the bar. After a protective film is vacuum-deposited on the end face mirror, the bar is again scribed in the stripe direction and indexed to separate the semiconductor laser element into individual chips of 300 μm.
[0060]
When a current was applied to the semiconductor laser device of the first embodiment, blue oscillation light having a wavelength of 410 nm was emitted from the end face.
[0061]
As a comparative example, the present inventor sets the p-type light guide layer to the same Cd as the n-type light guide layer 104._{0 . 05}Zn_{0 . 95}On the other hand, a semiconductor laser device having a layer other than the p-type light guide layer and a layer similar to the layer of the semiconductor laser device of the first embodiment was fabricated, and a laser emission experiment of this semiconductor laser device was performed. Was done. As a result, the lasing threshold current was doubled as compared with the semiconductor laser device of the first embodiment, and the device life was reduced to 1/10.
[0062]
According to the oxide semiconductor light emitting device of the first embodiment, the bandgap energy of the p-type light guide layer 106 is inclined so as to increase from the non-doped quantum well active layer 105 side to the p-type cladding layer 107 side. Therefore, the refractive index of the p-type light guide layer 106 is large on the non-doped quantum well active layer 105 side and small on the p-type cladding layer 107 side. Therefore, the oxide semiconductor light-emitting element can operate with a low current, and the reliability of the oxide semiconductor light-emitting element can be increased.
[0063]
Further, according to the oxide semiconductor light emitting device of the first embodiment, the p-type light guide layer 106 is made of Cd having a different composition._xZn_{1 − x}O layer 106b, Mg_yZn_{1 − y}Since the laminated structure using the O layer 106c is used, the refractive index and the band gap energy, which are difficult to control only by inclining the composition ratio, can be completely controlled up to a minute change. In addition, Mg having a large band gap energy_yZn_{1 − y}Since the O layer 106c is selected as one layer of the stacked structure, the confinement of carriers in the non-doped quantum well active layer 105 can be improved, and the oxide semiconductor light emitting device can have excellent optical characteristics.
[0064]
FIG. 3 shows the relationship between the vapor pressure of Zn, Cd, and Mg and the temperature. The interval between the vapor pressures on the vertical axis in FIG. 3 increases exponentially. As shown in FIG. 3, Cd is more likely to evaporate than Zn as the temperature rises. Therefore, when growing a CdZnO mixed crystal, if the supply ratio of Zn and Cd is constant, the temperature rises. As a result, Cd becomes much easier to evaporate, and the composition ratio of Cd decreases. As shown in FIG. 3, Zn evaporates more easily than Mg as the temperature rises. Therefore, when growing a MgZnO mixed crystal, if the supply ratio of Zn and Mg is constant, Mg Is increased.
[0065]
Therefore, as shown in the formation of the light guide layer 106, the p-type light guide layer 106 is grown while changing the growth temperature while keeping the supply rates of Zn and Cd or Mg constant. By simply doing so, the composition ratio of Cd to Zn or the composition ratio of Zn to Mg can be easily changed, and the band gap energy of the p-type light guide layer 106 can be easily tilted. The method using the difference in vapor pressure depending on the temperature can of course tilt the band gap energy of the p-type light guide layer more easily than the method of growing the light guide layer by controlling the supply ratio of the group II element. It is. In the first embodiment, the growth temperature is changed gradually without abrupt change, so that the growth of crystal defects can be suppressed. Further, after the growth of the active layer having a high Cd composition ratio, it is necessary to increase the temperature in order to grow the MgZnO cladding layer 107. Therefore, it is better to gradually change the growth temperature of the optical guide layer 106 to evaporate Cd. Thus, the element life can be improved.
[0066]
In the oxide semiconductor light emitting device of the first embodiment, the ridge stripe width is set to approximately 1.5 μm. However, if the ridge stripe width is set to approximately 0.5 to 3 μm, carrier injection efficiency is high, The kink level can be improved by cutting off the higher-order transverse mode, and a high-performance oxide semiconductor light-emitting element having a low operating voltage can be manufactured. If the width of the ridge stripe is smaller than 0.5 μm, the operating voltage increases and the reliability deteriorates. On the other hand, when the ridge stripe width is larger than 3 μm, the carrier injection efficiency becomes low, and it becomes impossible to cut off the higher-order transverse mode.
[0067]
Further, in the oxide semiconductor light emitting device of the first embodiment, the Mg composition of the current block layer 109 is set to 0.2 or less, but the Mg composition of the current block layer is higher than the composition ratio of the cladding layer, and When the ratio is less than or equal to 0.5, a real refractive index type waveguide mechanism can be realized, light absorption can be prevented, and the crystallinity of the current blocking layer can be improved. If the Mg composition of the current blocking layer is lower than the composition ratio of the cladding layer, light absorption occurs, and the laser oscillation threshold current increases. If the Mg composition of the current block layer is set to a value larger than 0.5, dislocations and the like occur in the current block layer, and the crystallinity of the current block layer deteriorates.
[0068]
In the oxide semiconductor light emitting device of the first embodiment, nitrogen (N) is used as an acceptor impurity to be doped into the p-type ZnO-based semiconductor layer. In place of the above, Ni group elements such as Li, Cu and Ag, and V group elements such as As and P may be used. When N, Li, or Ag having a high activation rate is used as an acceptor impurity to be doped into the p-type ZnO-based semiconductor layer, an oxide semiconductor light-emitting element having a small oscillation threshold current and a long element life can be manufactured. N is N₂Is preferable because a high-concentration doping can be performed while maintaining good crystallinity by irradiating during the crystal growth with the plasma.
[0069]
In the oxide semiconductor light emitting device of the first embodiment, Ga is used as a donor impurity to be doped into the n-type ZnO-based semiconductor layer, but a group III element is used as a donor impurity to be doped into the n-type ZnO-based semiconductor layer. B, Al, In, etc. may be used. When Ga or Al having a high activation rate in a ZnO-based semiconductor is used, an oxide semiconductor light-emitting element having a small oscillation threshold current and a long element life can be manufactured.
[0070]
In the oxide semiconductor light emitting device of the first embodiment, the p-type contact layer 108 is formed on the p-type MgZnO cladding layer 107, and the p-type ohmic electrode 111 is formed on the p-type contact layer 108. The p-type ohmic electrode may be formed directly on the p-type MgZnO cladding layer without providing the p-type contact layer. Note that when a contact layer is formed, the electric resistance of the oxide semiconductor light-emitting element can be reduced. When the material of the contact layer is limited to ZnO having excellent crystallinity as in the oxide semiconductor light emitting device of the first embodiment, the carrier concentration can be increased. If the p-type ZnO contact layer 108 is excessively doped with an acceptor impurity, the crystallinity deteriorates remarkably, and the element efficiency of the oxide semiconductor light-emitting element decreases. Therefore, the acceptor impurity has a carrier concentration of 5 × 10 5¹⁶~ 5 × 10¹⁹cm^{− 3}It is preferable that doping is performed so as to fall within the range.
[0071]
In the oxide semiconductor light emitting device of the first embodiment, the n-type ZnO single crystal substrate 101 is used as a substrate, but the substrate is a sapphire substrate, a spinel substrate, or a LiGaO substrate.₂An insulating substrate such as a substrate may be used, or a conductive substrate such as a SiC substrate or a GaN substrate may be used. When an insulating substrate is used, a part of the growth layer may be etched to expose the n-type ZnO buffer layer to form an n-type contact layer, on which an n-type ohmic electrode may be formed. As the n-type contact layer material formed by exposing the n-type ZnO buffer layer, ZnO is suitable as in the case of the p-type contact layer, and the doping concentration of the donor impurity is 1 × 10¹⁸~ 1 × 10²¹cm^{− 3}Is more preferable, and 5 × 10¹⁹~ 5 × 10²⁰cm^{− 3}Is preferably adjusted within the range described above. The thickness of the n-type contact layer formed by exposing the n-type ZnO buffer layer is 0.001 to 1 μm, preferably 0.005 to 0.5 μm, and more preferably 0.01 to 0.1 μm. Is preferably adjusted to the range described above. Even when an insulating substrate is used, an n-type buffer layer may be formed on the insulating substrate. In this case, a growth layer having excellent crystallinity can be formed on the n-type buffer layer. There are the following three conditions that the semiconductor substrate must satisfy in order to maximize the luminous efficiency in the visible region (1. The in-plane lattice constant difference from ZnO is 3% or less, The defect serving as the emission center can be reduced, 2. the absorption coefficient corresponding to the emission wavelength is low, 3. the substrate is a conductive substrate, and an electrode can be formed on the back surface), and the n-type ZnO single crystal substrate 101 has the above conditions. Is most preferable. When a layer is formed on the zinc surface of the n-type ZnO single crystal substrate 101 as a main surface as in the oxide semiconductor light emitting device of the first embodiment, the carrier activation rate of the p-type layer And a p-type layer having low resistance can be formed.
[0072]
In the oxide semiconductor light emitting device of the first embodiment, the p-type ZnO contact layer 108 and the n-type MgO_{0 . 2}Zn_{0 . 8}Ni was vacuum-deposited on the entire upper surface of the O current block layer 109 to form the p-type ohmic electrode 111. However, in the oxide semiconductor light emitting device of the present invention, the entire upper surface of the n-type contact layer and the n-type current block layer is provided. Then, Pt, Pd or Au may be deposited to form a p-type ohmic electrode, and two of Ni, Pt, Pd and Au may be formed on the entire upper surface of the n-type contact layer and the n-type current block layer. A p-type ohmic electrode may be formed by vapor deposition of the above metals. Incidentally, when the p-type ohmic electrode 111 is formed by evaporating Ni as in the oxide semiconductor light-emitting device of the first embodiment, the p-type ohmic electrode 111 is formed with the p-type ZnO contact layer 108 and the n-type MgO._{0 . 2}Zn_{0 . 8}The p-type ohmic electrode 111 can be easily fixed to the entire upper surface of the O current block layer 109 and the electric resistance of the p-type ohmic electrode 111 can be reduced.
[0073]
In the oxide semiconductor light emitting device of the first embodiment, the annealing process is not performed after the formation of the p-type ohmic electrode. However, in the oxide semiconductor light emitting device of the present invention, the annealing process is performed after the formation of the p-type ohmic electrode. In this case, the adhesion of the p-type ohmic electrode can be improved, and the electrical resistance of the p-type ohmic electrode can be reduced. In order to obtain an annealing effect without causing defects in the ZnO crystal, it is preferable to set the annealing temperature to 300 to 400 ° C.₂Alternatively, it is preferable to use an air atmosphere. Note that the atmosphere in the annealing process is N₂It has been found that setting to increases the electrical resistance of the p-type ohmic electrode.
[0074]
In the oxide semiconductor light emitting device of the first embodiment, the pad electrode for wire bonding is not provided on the p-type ohmic electrode 111. However, in the oxide semiconductor light emitting device of the present invention, the wiring to the lead frame is not provided. For simplicity, a pad electrode for wire bonding may be formed on the p-type ohmic electrode. When a pad electrode for wire bonding is formed on the p-type ohmic electrode, the pad electrode is preferably made of Au, which can be easily bonded and does not become a donor impurity even when diffused into ZnO. Another metal layer may be formed for the purpose of improving the adhesion between the p-type ohmic electrode and the pad electrode.
[0075]
In the oxide semiconductor light emitting device of the first embodiment, Al was vacuum-deposited on the back surface of the ZnO substrate 101 to form an n-type ohmic electrode. An n-type ohmic electrode may be formed by depositing Ti or Cr on the back surface, or an n-type ohmic electrode may be formed by depositing two or more metals of Ti, Cr and Al. When Al is selected as the metal to be deposited as in the first embodiment, the electric resistance of the n-type ohmic electrode can be reduced, and the manufacturing cost of the n-type ohmic electrode can be reduced. When Ti is selected as the metal to be deposited, the n-type ohmic electrode can be easily fixed to the back surface of the substrate.
[0076]
In the oxide semiconductor light emitting device of the first embodiment, Al is vacuum-deposited on the entire back surface of the ZnO substrate 101 to form the n-type ohmic electrode 110. In the oxide semiconductor light emitting device of the present invention, Al may be partially vacuum-deposited on the back surface of the semiconductor substrate, an Al n-type ohmic electrode may be patterned into an arbitrary shape, and the exposed back surface of the substrate may be bonded to a lead frame with an Ag paste or the like. Since the Al electrode has a high reflectance of blue to ultraviolet light, the light extraction efficiency is high even if it is formed on the entire back surface. However, since Ag has a higher reflectance of blue to ultraviolet light than Al, it has a high reflectance of blue to ultraviolet light. It is preferable because the emission output can be improved.
[0077]
In the oxide semiconductor light emitting device of the first embodiment, the oxide semiconductor light emitting device is manufactured by using the MBE method using a semiconductor material (solid or gaseous material). The device may be manufactured by a crystal growth technique such as a laser molecular beam epitaxy (laser MBE) method or a metal organic chemical vapor deposition (MOCVD) method. Further, an oxide semiconductor light-emitting element may be manufactured by combining at least two of the above-described MBE method, MOCVD method, and laser MBE method.
[0078]
In the oxide semiconductor light-emitting device of the first embodiment, the p-type light guide layer 106 is divided into three layers and the composition is graded. However, in the oxide semiconductor light-emitting device of the present invention, the p-type light guide layer is It may be composed of two layers of a CdZnO mixed crystal and a MgZnO mixed crystal with a gradient composition, or may be composed of a CdZnO mixed crystal with a gradient composition or a single layer of a MgZnO mixed crystal with a gradient composition.
[0079]
Further, in the oxide semiconductor light emitting device of the first embodiment, the p-type light guide layer 106 is formed of Cd_xZn_{1 − x}O layer 106b, Mg_yZn_{1 − y}Although the O-layer 106c is used to form a stacked structure of two layers having different compositions, in the oxide semiconductor light-emitting element of the present invention, the p-type light guide layer has a stacked structure of three or more layers having different compositions. May be.
[0080]
In the oxide semiconductor light emitting device of the first embodiment, while the n-type light guide layer 104 is composed of one layer, the p-type light guide layer 106 is divided into three layers and the composition is graded. In a semiconductor light emitting device, for example, an n-type light guide layer is formed by a 10 nm-thick Cd_{0 . 05}Zn_{0 . 95}O layer 204a, 10 nm thick Cd_xZn_{1 − x}O layer 204b and 10 nm thick Mg_yZn_{1 − y}While being composed of three layers of the O layer 204c, the Cd composition ratio x is gradually changed continuously from 0.05 to 0, and the Mg composition ratio y is gradually changed continuously from 0 to 0.1. And the p-type light guide layer may be constituted by a single layer, and even in this case, substantially the same effects as those of the oxide semiconductor light emitting device of the first embodiment can be obtained.
[0081]
In the oxide semiconductor light emitting device of the first embodiment, the first conductivity type is n-type and the second conductivity type is p-type. In the oxide semiconductor light-emitting device of the present invention, the first conductivity type is n-type. The p-type and the second conductivity type may be the n-type.
[0082]
In the oxide semiconductor light emitting device of the first embodiment, the Cd composition ratio x of the p-type light guide layer 106 is gradually changed continuously from 0.05 to 0, and the Mg composition ratio y is set to 0 to 0. .1, but the range of changing the composition ratio is not limited to the above range. Further, also in the case of the above-described modified example in which the p-type light guide layer is composed of one layer and the n-type light guide layer is composed of three layers, the Cd composition ratio x and the Mg composition ratio y are shown in the modified example. Of course, it is not limited to the range. Further, the composition ratio of each layer of the oxide semiconductor light emitting device of the present invention is not limited to the numerical value of the composition ratio of the corresponding layer specifically described in the oxide semiconductor light emitting device of the first embodiment. .
[0083]
(2nd Embodiment)
FIG. 4 is a band profile near an active layer of a ZnO-based semiconductor laser device that is an oxide semiconductor light emitting device according to the second embodiment of the present invention.
[0084]
4, an arrow C indicates a direction in which the band gap energy of the oxide semiconductor light emitting device of the second embodiment increases, and a curve D indicates the band gap energy of each layer of the oxide semiconductor light emitting device of the second embodiment. ing.
[0085]
The oxide semiconductor light emitting device of the second embodiment is made of n-type Mg_{0 . 1}Zn_{0 . 9}On the O-cladding layer 103, a 10 nm-thick Mg_yZn_{1 − y}O layer 204c (Mg composition ratio y continuously and gradually changes from 0 to 0.1), 10 nm thick Cd_xZn_{1 − x}O layer 204b (Cd composition ratio x continuously and gradually changes from 0.05 to 0), 10 nm thick Cd_{0 . 05}Zn_{0 . 95}The n-type light guide layer 204 is formed by laminating three O layers 204a in this order so that the band gap energy of the n-type light guide layer 204 in addition to the band gap energy of the p-type light guide layer 106 is also inclined. Only the differences are different from the oxide semiconductor light emitting device of the first embodiment.
[0086]
In the oxide semiconductor light emitting device of the second embodiment, the same components as those of the oxide semiconductor light emitting device of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Further, in the oxide semiconductor light emitting device of the second embodiment, the description of the same effects and modifications as those of the oxide semiconductor light emitting device of the first embodiment will be omitted, and the oxide semiconductor light emitting device of the first embodiment will be omitted. Only the functions and effects different from those of the light emitting element will be described.
[0087]
In the structure of the oxide semiconductor light emitting device of the second embodiment, the bandgap energy of the n-type light guide layer 204 is changed from the non-doped quantum well active layer 105 side to the n-type Mg._{0 . 1}Zn_{0 . 9}It is inclined so as to increase toward the O clad layer 103, and as shown in FIG. 4, the band gap energy is symmetrical above and below the non-doped quantum well active layer 105 with the non-doped quantum well active layer 105 as a boundary. Has become.
[0088]
After fabricating the structure of the oxide semiconductor light emitting device of the second embodiment, the ZnO substrate 101 was cleaved to form an end face mirror, a protective film was vacuum-deposited, and the device was separated to 300 μm. When a current was applied to the semiconductor laser device of the second embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the end face.
[0089]
In addition, the oxide semiconductor light emitting device of the second embodiment has an oscillation threshold current reduced by about 20%, a crystal defect is further reduced, and an oxide semiconductor light emitting device of the first embodiment. The element life was extended by about 20%.
[0090]
According to the oxide semiconductor light emitting device of the second embodiment, in addition to the p-type light guide layers 106 (106a, 106b and 106c), the band gap energy is symmetrical above and below the non-doped quantum well active layer 105. Since the n-type light guide layer 204 (204a, 204b, 204c) also has a composition gradient structure, the effect of confining light and carriers in the non-doped quantum well active layer 105 can be further improved.
[0091]
Further, according to the oxide semiconductor light emitting device of the second embodiment, the n-type light guide layer 204 is made of Cd having a different composition._xZn_{1 − x}O layer 204b, Mg_yZn_{1 − y}Since it has a laminated structure using the O layer 204c, the refractive index and the band gap energy, which are difficult to control only by inclining the composition ratio, can be completely controlled up to a minute change. In addition, Mg having a large band gap energy_yZn_{1 − y}Since the O layer 204c is selected as one layer of the stacked structure, the confinement of carriers in the non-doped quantum well active layer 105 can be improved, and the oxide semiconductor light emitting device can have excellent optical characteristics.
[0092]
In addition, in the oxide semiconductor light emitting device of the second embodiment, in addition to the p-type light guide layers 106 (106a, 106b and 106c), the band gap energy is symmetrical above and below the non-doped quantum well active layer 105. Thus, the n-type light guide layer 204 (204a, 204b and 204c) also has a compositionally graded structure, but the bandgap energy is not symmetrical above and below the non-doped quantum well active layer, and the bandgap energy of the n-type light guide layer is lower. Under the condition of increasing from the non-doped quantum well active layer side toward the n-type MgZnO cladding layer, in addition to the p-type light guide layers 106 (106a, 106b and 106c), the n-type light guide layers 204 (204a, 204b and 204c) May have a composition gradient structure.
[0093]
In the oxide semiconductor light emitting device of the second embodiment, the n-type light guide layer 204 is divided into three layers and the composition is graded. In the oxide semiconductor light emitting device of the present invention, the n-type light guide layer is It may be composed of two layers of a CdZnO mixed crystal and a MgZnO mixed crystal with a gradient composition, or may be composed of a CdZnO mixed crystal with a gradient composition or a single layer of a MgZnO mixed crystal with a gradient composition.
[0094]
In the oxide semiconductor light emitting device of the second embodiment, the p-type light guide layer 206 is formed of Cd_xZn_{1 − x}O layer 204b, Mg_yZn_{1 − y}The oxide semiconductor light emitting device of the present invention has an n-type light guide layer having a stacked structure of three or more layers having different compositions, although the O layer 204c is formed using the O layer 204c and has a stacked structure of two layers having different compositions. May be.
[0095]
(Third embodiment)
FIG. 5 is a structural perspective view of a ZnO-based semiconductor laser device that is an oxide semiconductor light emitting device according to a third embodiment of the present invention and a band profile near an active layer.
[0096]
In FIG. 5, an arrow E indicates a direction in which the band gap energy increases, and a curve F indicates the band gap energy of each layer.
[0097]
The oxide semiconductor light emitting device according to the third embodiment has a step-like shape such that the band gap energies of the n-type light guide layer 504 and the p-type light guide layer 506 are symmetrical above and below the non-doped quantum well active layer 105. The only difference from the oxide semiconductor light emitting device of the first embodiment is that the oxide semiconductor light emitting device is formed by using a laser MBE device.
[0098]
In the oxide semiconductor light emitting device of the third embodiment, the same components as those of the oxide semiconductor light emitting device of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Further, in the oxide semiconductor light emitting device of the third embodiment, description of the same operation effects and modifications as those of the oxide semiconductor light emitting devices of the first and second embodiments will be omitted, and the first and second embodiments will be omitted. Only the effects and modifications different from those of the oxide semiconductor light-emitting element of the embodiment mode will be described.
[0099]
The oxide semiconductor light emitting device of the third embodiment was formed by a laser MBE device (laser molecular beam epitaxy device) shown in FIG.
[0100]
In this laser MBE apparatus, a substrate holder 302 is disposed above a growth chamber 301 that can be evacuated to an ultra-high vacuum. A substrate 303 is fixed to the back surface of the substrate holder 302. When the substrate holder 302 is heated by a heater 304 disposed above the substrate holder 302, the substrate 303 is heated by the heat conduction. I have. A target table 305 is disposed directly below the substrate holder 302 at an appropriate distance, and a plurality of raw material targets 306 are disposed on the target table 305. The surface of the target 306 is ablated by the pulsed laser beam 308 emitted through the view port 307 provided on the side surface of the growth chamber 301, and the thin film is grown by the instantaneous evaporation of the raw material of the target 306 deposited on the substrate. It has become. The target table 305 has a rotation mechanism, and by controlling the rotation in synchronization with the irradiation sequence of the pulse laser beam 308, different target materials can be stacked on the thin film. The growth chamber 301 is provided with a plurality of gas introduction pipes (in FIG. 6, 310a and 301b are shown as examples) so that a plurality of gases can be introduced, and the atomic beam activated by the radical cell 309 is provided. Irradiation to the substrate is also possible. When the oxide semiconductor light-emitting device is manufactured by the laser MBE method as in the third embodiment, the composition deviation between the raw material target and the thin film can be reduced, and ZnGa₂O₄And other unintended by-products can be suppressed.
[0101]
Hereinafter, a method for manufacturing the oxide semiconductor light-emitting element of the third embodiment using a laser MBE apparatus will be described with reference to FIGS.
[0102]
First, the cleaned ZnO substrate 101 was introduced into a laser MBE apparatus,₂Heating is performed at a temperature of 600 ° C. for 30 minutes while flowing a gas for cleaning.
[0103]
Next, the substrate temperature was lowered to 450 ° C., and the non-doped ZnO single crystal and Ga₂O₃The ZnO sintered body to which is added is used as a raw material target, and the driving cycle of the target table by the rotating mechanism and the pulse irradiation cycle of the KrF excimer laser are synchronized by an external control device (not shown), so that the raw material target has a desired Ga doping concentration. The n-type ZnO buffer layer 102 is grown alternately by ablation at the obtained ratio. KrF excimer laser (wavelength: 248 nm, pulse number: 10 Hz, output 1 J / cm) is used as a pulse laser for ablation.²) Was used. During the growth, O₂Gas was introduced.
[0104]
Next, the substrate temperature was raised to 500 ° C., and further, a non-doped ZnO single crystal and Ga₂O₃The MgZnO sintered body to which n is added is used as a raw material target, and alternately ablation is performed at a ratio at which a desired Mg composition ratio and a Ga doping concentration can be obtained._{0 . 1}Zn_{0 . 9}The O clad layer 103 is grown.
[0105]
Next, the light guide layer 504 is formed. First, the temperature of the substrate was lowered to 475 ° C., and the non-doped ZnO single crystal and Ga were removed.₂O₃The MgZnO sintered body to which n is added is used as a raw material target, and alternately ablation is performed at a ratio at which a desired Mg composition ratio and a Ga doping concentration can be obtained._{0 . 1}Zn_{0 . 9}10 nm n-type Mg on the O cladding layer 103_{0 . 05}Zn_{0 . 95}After growing the O light guide layer 504c, the substrate temperature is lowered to 450 ° C., and the non-doped ZnO single crystal and Ga₂O₃Is used as a raw material target, and alternately ablation is performed at a ratio to obtain a desired Ga doping concentration to grow an n-type ZnO optical guide layer 504b of 10 nm. Then, after lowering the substrate temperature to 425 ° C., the non-doped ZnO single crystal and the Ga₂O₃The CdZnO sintered body to which N is added is used as a raw material target, and ablation is alternately performed at a ratio at which a desired Cd composition ratio and a Ga doping concentration can be obtained._{0 . 05}Zn_{0 . 95}The O light guide layer 504a is grown.
[0106]
Next, the substrate temperature was lowered to 400 ° C., and the non-doped ZnO single crystal and Ga₂O₃The CdZnO sintered body to which Cd is added is used as a raw material target, and alternately ablated at a ratio that can obtain a desired Cd composition ratio, thereby obtaining Cd_{0 . 05}Zn_{0 . 95}O barrier layer and Cd_{0 . 1}Zn_{0 . 9}O-well layers are alternately stacked to grow the non-doped quantum well active layer 105.
[0107]
Thereafter, the substrate temperature was raised to 425 ° C., and N introduced through the gas introduction pipe 310b.₂While irradiating the plasma with the gas in the radical cell 309, the non-doped ZnO single crystal and the non-doped CdZnO sintered body are used as the raw material targets, and the ablation is alternately performed at a ratio that can obtain a desired Cd composition ratio and an N doping concentration. 10 nm p-type Cd on layer 105_{0 . 05}Zn_{0 . 95}An O light guide layer 506a was grown.
[0108]
Next, the substrate temperature was raised to 450 ° C., and N introduced through the gas introduction pipe 310b.₂Ablation is performed by using a non-doped ZnO single crystal as a raw material target while irradiating the gas with a plasma in a radical cell 309 to obtain p-type Cd._{0 . 05}Zn_{0 . 95}A 10 nm p-type ZnO light guide layer 506b was grown on the O light guide layer 506a.
[0109]
Next, the temperature of the substrate was raised to 475 ° C., and N introduced through the gas introduction pipe 310b was introduced.₂While irradiating the plasma with the gas in the radical cell 309, the non-doped ZnO single crystal and the non-doped MgZnO sintered body are used as a raw material target, and alternately ablation is performed at a ratio that can obtain a desired Mg composition ratio and an N doping concentration, thereby forming a p-type ZnO light. On the guide layer 506b, 10 nm of p-type Mg_{0 . 05}Zn_{0 . 95}The O light guide layer 506c is grown.
[0110]
Next, the temperature of the substrate was raised to 500 ° C. and N introduced through the gas introduction pipe 310b.₂Alternating ablation is performed by using a non-doped ZnO single crystal and a non-doped MgZnO sintered body as a raw material target while irradiating the gas with plasma generated in a radical cell 309 to obtain p-type Mg._{0 . 1}Zn_{0 . 9}The O clad layer 107 is grown.
[0111]
Next, N introduced through the gas introduction pipe 310b₂Ablation is performed using a non-doped ZnO single crystal as a raw material target while irradiating the gas with plasma generated in a radical cell 309 to grow a p-type ZnO contact layer 108.
[0112]
Next, the substrate 101 is taken out of the laser MBE apparatus, and the p-type ZnO contact layer 108 and the p-type Mg_{0 . 1}Zn_{0 . 9}A part of the O-clad layer 107 is etched into a ridge shape having a width of 1.5 μm.
[0113]
Next, the substrate 101 is again introduced into the laser MBE apparatus, the substrate temperature is raised to 550 ° C., and the non-doped ZnO single crystal and Ga₂O₃The MgZnO sintered body to which n is added is used as a raw material target, and alternately ablation is performed at a ratio at which a desired Mg composition ratio and a Ga doping concentration can be obtained._{0 . 2}Zn_{0 . 8}The O current blocking layer 109 is grown.
[0114]
Finally, the substrate 101 is taken out of the laser MBE apparatus, and n-type Mg deposited on the ridge stripe is removed._{0 . 2}Zn_{0 . 8}The O layer is etched away to expose the p-type ZnO contact layer 108, and the n-type MgO_{0 . 2}Zn_{0 . 8}100 nm thick Ni is vacuum-deposited on the entire upper surface including the O flow blocking layer 109 to form a p-type ohmic electrode 111, and 100 nm thick Al is vacuum-deposited on the back surface of the ZnO substrate 101 to form n. A type ohmic electrode 110 is formed.
[0115]
After fabricating the structure of the oxide semiconductor light emitting device of the third embodiment, the ZnO substrate 101 of the third embodiment was cleaved to form an end face mirror, a protective film was vacuum-deposited, and the device was separated to 300 μm. When a current was applied to the semiconductor laser device of the third embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the end face. The oxide semiconductor light-emitting device of the third embodiment had substantially the same oscillation threshold current and device life as the oxide semiconductor light-emitting device of the second embodiment.
[0116]
In the laser MBE method, since the raw material is supplied in a pulse shape, it is difficult to continuously change the growth conditions such as the supply amount. However, as shown in FIG. 5, the n-type light guide layer 504 and the p-type light guide layer If the bandgap energy is changed stepwise and discontinuously stepwise, the laser MBE method can be used.
[0117]
According to the oxide semiconductor light emitting device of the third embodiment, the growth conditions of the n-type light guide layer 504 and the p-type light guide layer 506 are changed stepwise and discontinuously stepwise, so that the composition ratio is changed stepwise. Therefore, it is possible to use a crystal growth technique such as a laser MBE method in which a continuous change in conditions is difficult, and the composition can be easily tilted using a laser MBE method or the like. From this, a growth method suitable for an oxide crystal can be selected according to the situation, so that the emission characteristics of the oxide semiconductor light-emitting element can be improved, the reliability of the oxide semiconductor light-emitting element can be increased, and the light guide can be improved. The same effect as that shown in FIG. 4 in which the band gap energies of the layers 106 and 204 are continuously inclined can be obtained.
[0118]
In the oxide semiconductor light emitting device of the third embodiment, the bandgap energy of the light guide layer is changed in three steps in a staircase. In the oxide semiconductor light emitting device of the present invention, the bandgap energy of the light guide layer is changed. The energy may be changed in two or more steps other than the three steps, and in this case, the same operation and effect as in the third embodiment can be obtained.
[0119]
In the oxide semiconductor light-emitting device of the third embodiment, both the n-type light guide layer 504 and the p-type light guide layer 506 are converted from the non-doped quantum well active layer 105 to the n-type clad layer 103 or the laser MBE device. In order to increase the band gap energy toward the p-type cladding layer 107, it is discontinuously inclined stepwise so as to increase the band gap energy, and the band gap energy is symmetrical above and below the non-doped quantum well active layer 105. Although each of the three layers is constituted, in the oxide semiconductor light emitting device of the present invention, only one of the n-type light guide layer and the p-type light guide layer is directed from the non-doped quantum well active layer to the n-type clad layer or the p-type clad layer. It goes without saying that the n-type light guide may be discontinuously inclined stepwise so as to increase the band gap energy. In the case of the 504 and both the band gap energy of the p-type optical guide layer 506 is inclined, both the band gap energy, it is of course may not become symmetrical in the upper and lower non-doped quantum well active layer.
[0120]
(Fourth embodiment)
FIG. 7 is a band profile near an active layer of a ZnO-based semiconductor laser device that is an oxide semiconductor light emitting device according to the fourth embodiment of the present invention.
[0121]
In FIG. 7, an arrow G indicates a direction in which the band gap energy increases, and a curve J indicates the band gap energy of each layer.
[0122]
In the oxide semiconductor light emitting device of the fourth embodiment, the n-type light guide layer 404 and the p-type light guide layer 406 have a superlattice structure of CdZnO, ZnO and MgZnO with a thickness of 4 nm, and the band gap energy is inclined. Only the point is different from the oxide semiconductor light emitting device of the third embodiment.
[0123]
In addition, as shown in FIG. 7, the above-mentioned superlattice structure has a band gap energy that repeats large and small by repeating a plurality of the CdZnO, ZnO, and MgZnO layers each having a thickness of 4 nm, and a gap energy well. It is assumed that lines (or curves) H and I connecting the middle of the depth increase from the non-doped quantum well active layer 105 to the n-type cladding layer 102 or the p-type cladding layer 107.
[0124]
In the oxide semiconductor light emitting device of the fourth embodiment, descriptions of configurations, functions, effects, and modifications common to those of the oxide semiconductor light emitting device of the third embodiment are omitted. Only different configurations, effects, and modifications will be described.
[0125]
When a current was applied to the oxide semiconductor light emitting device of the fourth embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the end face. The oscillation threshold current was reduced by 10% as compared with the second embodiment, and the device life was shortened. Is 10% longer.
[0126]
According to the oxide semiconductor light emitting device of the fourth embodiment, the n-type light guide layer 404 and the p-type light guide layer 406 have a superlattice structure and the band gap energy is inclined. The change in gap energy can be more finely controlled. Further, the carrier mobility can be increased, the oscillation threshold current can be reduced, and the reliability can be improved.
[0127]
In the oxide semiconductor light emitting device according to the fourth embodiment, the H and I monotonously increase. However, a line (or curve) connecting the gap energy between the well depths is a non-doped quantum well active layer. From the top to the n-type cladding layer or the p-type cladding layer as long as it increases as a whole, and may decrease locally.
[0128]
(Fifth embodiment)
FIG. 8 is a band profile near an active layer of a ZnO-based semiconductor laser device that is an oxide semiconductor light emitting device according to the fifth embodiment of the present invention.
[0129]
In FIG. 8, an arrow K indicates a direction in which the band gap energy increases, and a curve L indicates the band gap energy of each layer.
[0130]
The oxide semiconductor light emitting device of the fifth embodiment is an n-type Mg semiconductor._{0 . 1}Zn_{0 . 9}Between the O-cladding layer 103 and the n-type light guide layer 204, a 5 nm-thick n-type Mg_{0 . 2}Zn_{0 . 8}An O carrier overflow suppression layer 112 is formed, and the p-type light guide layer 106 and the p-type Mg_{0 . 1}Zn_{0 . 9}A p-type Mg layer having a thickness of 5 nm_{0 . 2}Zn_{0 . 8}Only the point of forming the O carrier overflow suppression layer 113 is different from the oxide semiconductor light emitting device of the second embodiment.
[0131]
In the oxide semiconductor light emitting device according to the fifth embodiment, descriptions of configurations, functions, effects, and modifications common to the oxide semiconductor light emitting device according to the second embodiment are omitted, and the oxide semiconductor light emitting device according to the second embodiment is different from the oxide semiconductor light emitting device according to the second embodiment. Only different configurations, effects, and modifications will be described.
[0132]
When a current was applied to the oxide semiconductor light emitting device of the fifth embodiment, blue oscillation light having a wavelength of 410 nm was obtained from the end face, and the oscillation threshold current was reduced by 20% as compared with the second embodiment, and the device life was shortened. Is 10% longer.
[0133]
According to the oxide semiconductor light emitting device of the fifth embodiment, the band gap energy between the n-type cladding layer 103 and the n-type light guide layer 204 is larger than that of the n-type cladding layer 103. The n-type MgZnO carrier overflow suppressing layer 112 is formed, and the band gap energy between the p-type optical guide layer 106 and the p-type MgZnO cladding layer 107 is larger than that of the p-type optical guide layer 106 and the p-type MgZnO cladding layer 107. Since the p-type MgZnO carrier overflow suppression layer 113 is formed, carrier overflow from the active layer can be suppressed, and the luminous efficiency of the oxide semiconductor light emitting element can be improved.
[0134]
In the oxide semiconductor light emitting device of the fifth embodiment, the n-type MgZnO carrier overflow suppression layer 112 is formed between the n-type cladding layer 103 and the n-type light guide layer 204, and the p-type light guide layer 106 Although the p-type MgZnO carrier overflow suppression layer 113 is formed between the p-type MgZnO cladding layers 107, one of the n-type MgZnO carrier overflow suppression layer 112 and the p-type MgZnO carrier overflow suppression layer 113 may be omitted. . The n-type MgZnO carrier overflow suppression layer and the p-type MgZnO carrier overflow suppression layer having a large band gap energy may be symmetric or asymmetric above and below the non-doped quantum well active layer 105.
[0135]
According to the oxide semiconductor light emitting devices of the first to fifth embodiments, since the non-doped quantum well active layer 105 has a quantum well structure, the oxide semiconductor light emitting device has excellent polarization selectivity and large optical characteristics. An element having gain and characteristic temperature can be obtained. According to the oxide semiconductor light emitting devices of the first to fifth embodiments, the bandgap energy of the light guide layer is increased from the non-doped quantum well active layer 105 side to the clad layers 103 and 107 side. The refractive index of the light guide layer can be increased on the active layer side and decreased on the clad layer side, and the light confinement of the non-doped quantum well active layer 105 can be increased. Therefore, the emission characteristics of the oxide semiconductor light-emitting element can be further improved.
[0136]
In the oxide semiconductor light emitting devices of the first to fifth embodiments, the non-doped quantum well active layer 105 having the quantum well structure is employed. However, the quantum well structure need not be employed for the active layer. Further, in the present invention, an active layer using a dope may be employed.
[0137]
In the oxide semiconductor light emitting devices of the first to fifth embodiments, the first conductivity type is n-type and the second conductivity type is p-type. However, the first conductivity type is p-type and the second conductivity type is p-type. The type may be n-type.
[0138]
Further, the composition ratio of each layer of the oxide semiconductor light emitting device of the present invention is not limited to the numerical value of the composition ratio of each layer specifically described in the oxide semiconductor light emitting devices of the first to fifth embodiments. .
[0139]
Further, the oxide semiconductor light emitting device of the present invention may be manufactured by partially combining at least two or more of the oxide semiconductor light emitting devices of the first to fifth embodiments. Of course.
[0140]
【The invention's effect】
As is clear from the above, the oxide semiconductor light-emitting device of the present invention has a structure in which at least a first conductivity type clad layer, a first conductivity type light guide layer, an active layer, and a second layer made of a ZnO-based semiconductor are formed above a substrate. An oxide semiconductor light emitting device in which a conductive type light guide layer and a second conductive type clad layer are stacked in this order, wherein the band gap energy of the second conductive type light guide layer is the band gap energy of the active layer. Larger, and smaller than the bandgap energy of the second conductivity type cladding layer, and the bandgap energy of the second conductivity type light guide layer increases as approaching from the active layer side to the second conductivity type cladding layer side. As a result, the light confinement effect can be increased, the oscillation threshold current can be reduced, and crystal defects can be reduced. That. In addition, operation can be performed with a low current, and reliability can be increased.
[0141]
Further, according to the method of manufacturing an oxide semiconductor light emitting device of the present invention, the first conductivity type cladding layer, the first conductivity type light guide layer, the active layer, and the second conductivity type light are formed above the substrate. A method of manufacturing an oxide semiconductor light emitting device, wherein a guide layer and a second conductivity type clad layer are stacked in this order, wherein the supply speed of Cd is kept constant or changed. Then, at least a portion made of a ZnO-based semiconductor containing Cd in at least one of the second conductivity type guide layer and the first conductivity type guide layer is grown at a different growth temperature, so that the substrate is formed on the substrate. In a vertical direction, the ratio of Cd to Zn in at least a part of the band is changed to change the band gap of at least one of the second conductivity type guide layer and the first conductivity type guide layer. A step of inclining the energy, and keeping or changing the supply rate of Mg from the Mg-containing ZnO-based semiconductor in at least one of the second conductivity type guide layer and the first conductivity type guide layer. The second conductivity type guide layer and the first conductivity type are formed by changing the ratio of Mg to Zn in the at least one portion in a direction perpendicular to the substrate by growing at least a portion of the guide layer at a growth temperature. Since at least one of the steps of inclining the band gap energy of at least one of the guide layers is provided, an oxide semiconductor light emitting device with a simple manufacturing process and excellent productivity can be manufactured.
[Brief description of the drawings]
FIG. 1 is a structural perspective view of an oxide semiconductor light emitting device according to a first embodiment of the present invention and a diagram showing a band profile near an active layer.
FIG. 2 is a plan view of a molecular beam epitaxy apparatus used for manufacturing the oxide semiconductor light emitting device of the first embodiment.
FIG. 3 is a diagram showing the relationship between the vapor pressure of Zn, Cd, and Mg and the temperature.
FIG. 4 is a diagram illustrating a band profile near an active layer of an oxide semiconductor light emitting device according to a second embodiment of the present invention.
5A and 5B are a perspective view of a structure of an oxide semiconductor light emitting device according to a third embodiment of the present invention and a diagram showing a band profile near an active layer.
FIG. 6 is a plan view of a laser molecular beam epitaxy apparatus used for manufacturing the oxide semiconductor light emitting device of the third embodiment.
FIG. 7 is a diagram illustrating a band profile near an active layer of an oxide semiconductor light emitting device according to a fourth embodiment of the present invention.
FIG. 8 is a diagram showing a band profile near an active layer of an oxide semiconductor light emitting device according to a fifth embodiment of the present invention.
[Explanation of symbols]
101 ZnO substrate
102 n-type ZnO buffer layer
103 n-type MgZnO cladding layer
104, 204, 404, 504 n-type light guide layer
105 Non-doped quantum well active layer
106, 406, 506 p-type light guide layer
107 p-type MgZnO cladding layer
108 p-type ZnO contact layer
109 n-type MgZnO current block layer
110 n-type ohmic electrode
111 p-type ohmic electrode
112 n-type MgZnO carrier overflow suppression layer
113 p-type MgZnO carrier overflow suppression layer
201 Growth Room
202 substrate holder
203 substrate
204 heater
205 evaporation cell
206 heater
207 Shutter
208 Radical cell
301 Growth Room
302 substrate holder
303 substrate
304 heater
305 Target table
306 Raw material target
307 viewport
308 pulse laser beam (excimer laser)
309 radical cell
310a, 310b Gas inlet pipe

Claims (12)

A first conductive type clad layer, a first conductive type light guide layer, an active layer, a second conductive type light guide layer, and a second conductive type clad layer made of at least a ZnO-based semiconductor are laminated on a substrate in this order. And
The band gap energy of the second conductivity type light guide layer is equal to or greater than the band gap energy of the active layer and equal to or less than the band gap energy of the second conductivity type cladding layer.
An oxide semiconductor light emitting device, wherein the bandgap energy of the light guide layer of the second conductivity type is inclined so as to increase from the active layer side to the cladding layer side of the second conductivity type. The oxide semiconductor light emitting device according to claim 1,
The bandgap energy of the first conductivity type light guide layer is equal to or greater than the bandgap energy of the active layer and equal to or less than the bandgap energy of the first conductivity type cladding layer.
An oxide semiconductor light emitting device, wherein the bandgap energy of the first conductivity type light guide layer is inclined so as to increase from the active layer side toward the first conductivity type clad layer side. The oxide semiconductor light emitting device according to claim 1,
At least one of the first conductivity type light guide layer and the second conductivity type light guide layer has a laminated structure in which two or more layers having different compositions are laminated. element. The oxide semiconductor light emitting device according to claim 3,
The oxide semiconductor light-emitting element, wherein the stacked structure includes a superlattice structure of ZnO-based semiconductors having different compositions. The oxide semiconductor light emitting device according to claim 1, wherein
An oxide semiconductor light emitting device, wherein an inclined band gap energy of at least one of the first conductivity type light guide layer and the second conductivity type light guide layer changes stepwise discontinuously. The oxide semiconductor light emitting device according to claim 1, wherein
When the band gap energy of the first conductivity type light guide layer is not inclined so as to increase as approaching the first conductivity type clad layer side from the active layer side,
A second conductivity type carrier having a larger band gap energy than the second conductivity type light guide layer and the second conductivity type cladding layer between the second conductivity type light guide layer and the second conductivity type cladding layer; Forming an overflow suppression layer,
When the bandgap energy of the first conductivity type light guide layer is increased so as to increase from the active layer side to the first conductivity type clad layer side,
A second conductivity type carrier having a band gap energy between the second conductivity type light guide layer and the second conductivity type cladding layer, which is larger than that of the second conductivity type light guide layer and the second conductivity type cladding layer; It has a larger band gap energy between the overflow suppression layer, the first conductivity type light guide layer, and the first conductivity type clad layer than the first conductivity type light guide layer and the first conductivity type clad layer. An oxide semiconductor light emitting device, wherein at least one of the first conductivity type carrier overflow suppression layers is formed. The oxide semiconductor light emitting device according to claim 1,
An oxide semiconductor light emitting device, wherein the active layer has a quantum well structure. A first conductivity type clad layer, a first conductivity type light guide layer, an active layer, a second conductivity type light guide layer, and a second conductivity type clad layer made of at least a ZnO-based semiconductor are laminated on a substrate in this order. A method for producing an oxide semiconductor light emitting device, which comprises producing an oxide semiconductor light emitting device,
A layer made of a ZnO-based semiconductor containing at least a portion of Cd in at least one of the second conductivity type light guide layer and the first conductivity type light guide layer is provided at a constant supply rate of Cd and Zn and at a growth temperature. By changing the ratio of Cd to Zn in at least a part of the light guide layer in a direction substantially perpendicular to the substrate, the second conductive type light guide layer and the first conductive type light guide layer A step of inclining at least one band gap energy,
A layer made of a ZnO-based semiconductor containing at least a portion of Mg in at least one of the second conductivity type light guide layer and the first conductivity type light guide layer is provided at a constant supply rate of Zn and Mg and at a growth temperature. By changing the ratio of Mg to Zn in at least a part of the light guide layer in a direction substantially perpendicular to the substrate, the second conductive type light guide layer and the first conductive type light guide layer A method for manufacturing an oxide semiconductor light emitting device, comprising: at least one step of inclining at least one band gap energy. A first conductivity type clad layer, a first conductivity type light guide layer, an active layer, a second conductivity type light guide layer, and a second conductivity type clad layer made of at least a ZnO-based semiconductor are laminated on a substrate in this order. A method for producing an oxide semiconductor light emitting device, which comprises producing an oxide semiconductor light emitting device,
A layer made of a ZnO-based semiconductor containing at least a portion of Cd in the second conductivity type light guide layer is grown on the substrate by reducing the supply rate of Cd and changing the growth temperature. Changing the ratio of Cd to Zn in at least a portion of the light guide layer in a vertical direction to incline the bandgap energy of the light guide layer of the second conductivity type; By growing the layer made of the ZnO-based semiconductor including the Cd supply rate and increasing the growth temperature, the ratio of Cd to Zn in at least a portion of the Zn in a direction substantially perpendicular to the substrate. And inclining the bandgap energy of the light guide layer of the first conductivity type. And the extent,
By growing a layer made of a ZnO-based semiconductor containing at least a part of Mg in the second conductivity type light guide layer under the condition of increasing the supply rate of Mg and changing the growth temperature, the layer is substantially formed on the substrate. Changing the ratio of Mg to Zn in the at least one portion in a vertical direction to incline the bandgap energy of the light guide layer of the second conductivity type; and removing at least a portion of the Mg in the light guide layer of the first conductivity type. By growing a layer comprising a ZnO-based semiconductor containing Mg under a condition in which the supply rate of Mg is reduced and the growth temperature is changed, the ratio of Mg to Zn in at least a portion of the Zn in a direction substantially perpendicular to the substrate. And inclining the bandgap energy of the light guide layer of the first conductivity type. Method of manufacturing an oxide semiconductor light-emitting device, characterized in that it comprises at least one of the steps of the extent. The method for manufacturing an oxide semiconductor light emitting device according to claim 8 or 9,
An oxide semiconductor light-emitting element, wherein a growth temperature for growing at least one of the layer made of the ZnO-based semiconductor containing Cd and the layer made of the ZnO-based semiconductor containing Mg is continuously changed. Manufacturing method. The method for manufacturing an oxide semiconductor light emitting device according to claim 8 or 9,
An oxide semiconductor light emitting device, wherein a growth temperature for growing at least one of a layer made of a ZnO-based semiconductor containing Cd and a layer made of a ZnO-based semiconductor containing Mg is changed stepwise. Manufacturing method. The method for manufacturing an oxide semiconductor light emitting device according to claim 9,
A method for manufacturing an oxide semiconductor light-emitting device, wherein the supply speed of at least one of Cd and Mg is changed stepwise.

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