JPH09307190A - Aluminum-indium-gallium-nitrogen based semiconductor luminous element and semiconductor luminous device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce impedance in an AlInGaN system semiconductor luminous element. SOLUTION: In this semiconductor luminous element, these are stacked in this order an n-GaN low temperature buffer layer 2, an n-GaN buffer layer 3, an n-In0.1 Ga0.9 N buffer layer 4, an n-Alx3 Ga1-x3 N clad layer 5, an n-GaN optical waveguide layer 6, an Inx-1 Ga1-x3 N/Inx2 Ga1-x2 N distortion multiple quantum well activation layer 7 (x1>x2), a p-GaN optical waveguide layer 8, a p-Alx3 Ga1-x3 N first clad layer 9, an n-A1x 4Ga1-x4 current prevention layer 10 having a striped current implantation window (x4>x3), a p-Alx3 Ga1-x3 N second clad layer 11, a p-GaN cap layer 12, and a p-SiC contact layer 13, on a sapphire substrate 1, and a part of the laminated part is removed by etching until the n-GaN buffer layer 3 is exposed. Thereafter, a p-side electrode 15 is formed on the p-SiC contact layer 13, and an n-side electrode 14 is formed on n-GaN buffer layer exposed by etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, and more particularly, to a structure of an AlInGaN based semiconductor light emitting device including a light emitting diode (LED) and a semiconductor laser, and a semiconductor light emitting using the AlInGaN based semiconductor light emitting device. It relates to the device.

[0002]

2. Description of the Related Art Although the shortest wavelength that can obtain a minute spot is the 630 nm band, which has been practically used in conventional semiconductor lasers, the wavelength band of 500 nm or less is used in the high density optical disk memory and printing fields using photosensitive materials. A single-mode laser with a Gaussian high-quality beam is expected.

As a conventional laser having a wavelength band of 500 nm or less, Jpn. J. Appl. Phys. Vol. 35 Pt. 2, No. 1B (1996) p.
As shown in p.L74-L76, low-temperature grown GaN buffer layer, n-GaN buffer layer, In _0.1 Ga _0.9 N layer, and n-Al at normal growth temperature were grown on sapphire substrate by metalorganic vapor phase epitaxy.
_0.15 Ga _0.85 N Clad layer, n-GaN optical waveguide layer, In _0.05 Ga
_0.95 N / In _0.2 Ga _0.8 N Strained multiple quantum well active layer, p-Al _0.2 G
a _0.8 N layer, p-GaN optical waveguide layer, p-Al _0.15 Ga _0.85 N clad layer, p-GaN contact layer are stacked and etched halfway through the n-GaN buffer layer by dry etching to form a cavity mirror By forming a region for forming an end face and an n-side electrode, and then forming an n-side and a p-side electrode, a 410 nm band multimode oscillation semiconductor laser is realized.

In the above AlInGaN semiconductor laser, p-Ga
Since the contact resistance between the N contact layer and the electrode and the resistivity of the p-GaN contact layer itself are extremely high, the operating voltage during pulse driving becomes as high as several tens of volts, and the power that is input to the device during oscillation is normally high. Since it is about 10 times larger than the element,
There are drawbacks such as heat generation of the element and large distortion during modulation. Therefore, reduction of the impedance of the element has been an issue.

Further, in the above AlInGaN semiconductor laser, in order to realize a single mode laser, it is necessary to narrow the stripe width of a built-in optical waveguide for stabilizing the transverse mode.

[0006]

However, the above-mentioned Al
When a narrow stripe is provided in the InGaN semiconductor laser, the contact area between the p-GaN contact layer and the electrode is reduced, which further increases the impedance.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an AlInGaN-based semiconductor light-emitting device with reduced impedance and a semiconductor light-emitting device using the AlInGaN-based semiconductor light-emitting device. To do.

[0008]

The AlInGaN semiconductor light-emitting device of the present invention is an AlInGaN-based semiconductor device in which at least a first conductivity type clad layer, an active layer, and a second conductivity type first clad layer are laminated in this order on a substrate. In the semiconductor light emitting device, a first conductivity type current blocking layer having a stripe-shaped current injection window is laminated on the second conductivity type first clad layer, and the current injection window is further covered on the current blocking layer. And a second conductivity type second clad layer and a second conductivity type contact layer are laminated in this order to form an internal current confinement mechanism, and a resonator surface is formed on two opposing end faces parallel to the lamination direction. Electrodes are formed on the second conductive type contact layer and on the substrate side, respectively.

In the above description, the fact that the electrode is formed on the substrate side means that the electrode is formed on the surface of the substrate which is not the semiconductor laminated surface or on the buffer layer laminated on the substrate. Further, it means that the first conductivity type and the second conductivity type have different conduction mechanisms. For example, when the first conductivity type is n-type conduction, the second conductivity type is p-type conduction. If the first conductivity type is p-type, the second conductivity type is n-type.

When the first conductivity type and the second conductivity type are n type and p type, respectively, the second conductivity type contact layer is preferably a p-SiC semiconductor layer, and the first conductivity type is And the second conductivity type is p-type and n-type, respectively, the substrate is preferably a p-SiC semiconductor.

It is desirable that a refractive index guided type is provided by providing a refractive index step in the joint surface between the second conductive type and second conductive type cladding layers and the first conductive type current blocking layer. The refractive index step can be adjusted, for example, by changing the thickness or composition of the first conductivity type current blocking layer.

That is, the AlInGaN-based semiconductor light-emitting device of the present invention has an internal stripe structure having a current confinement layer provided therein to increase the contact area between the contact layer and the electrode to reduce the contact resistance. A material having a low contact resistance with an electrode is used as a contact layer or a substrate to reduce the impedance of the element.

Furthermore, the stripe-shaped current injection window may be formed in a tapered shape from one end surface to the other end surface of the resonator.

The semiconductor light emitting device of the present invention is characterized by including an AlInGaN semiconductor light emitting device having a tapered current injection window having a predetermined reflectance coat on the two end faces.

Of the two end faces of the resonator, a predetermined reflectance coat applied to the one end face is a high reflection coat having a reflectance of 90% or more, and a predetermined reflectance coat applied to the other end face. A single mode laser, a super luminescence diode, or the like can be formed as a low reflection coat having a reflectance of 1% or less.

The predetermined reflectance coating applied to the two end faces is a non-reflection coating, and the semiconductor light emitting device further comprises a second harmonic generating section for generating a second harmonic incident on the semiconductor light emitting device. The light emitting element may amplify and output the second harmonic wave entered from the second harmonic wave generation section.

Further, of the two end faces of the resonator,
The predetermined reflectance coat applied to the one end face is a non-reflection coat, and the predetermined reflectance coat applied to the other end face is a low reflection coat having a reflectance of 1% or less, and the wavelength of incident light is selected. And a wavelength selecting section that reflects light is disposed on the one end surface side of the semiconductor light emitting element on which the non-reflection coating is applied, and the wavelength selecting section has a wavelength of light emitted from the one end surface of the semiconductor light emitting element. It is also possible to make a selection and return the selected light to the one end face, thereby emitting a single mode laser.

[0018]

In the AlInGaN-based semiconductor light emitting device of the present invention, the contact area between the contact layer and the electrode can be made large by adopting the internal stripe structure in which the current injection window, that is, the current confinement mechanism is provided. As compared with the conventional device structure, the impedance can be reduced even in a single mode semiconductor laser having a current confinement mechanism with a narrow stripe width. By reducing this impedance, it is possible to suppress heat generation of the element during high-power laser oscillation and perform stable oscillation.

The impedance can be further reduced by using p-SiC for the contact layer or the substrate which is the contact surface between the p-side electrode and the element.

By providing a refractive index step in the pn (np) junction surface, a refractive index waveguide type laser can be obtained, and thereby a Gauss type high quality beam can be realized.

Further, by forming the stripe in a taper shape from one end surface to the other end surface, in a high power laser, a kink is suppressed in the current / light output characteristics due to spatial hole burning of carriers to be injected, and emission is performed. By widening the side, the light density at the end face can be reduced, and deterioration due to optical damage at the end face can be prevented.

The semiconductor light-emitting device of the present invention can oscillate a stable short-wavelength laser by using the semiconductor light-emitting device having the above-mentioned tapered stripe in which the reflectance of the coat on the cavity surface is controlled.

As a result, the speed and quality of a hard copy output system for printing, photographs, medical images, etc. using these semiconductor light emitting elements and semiconductor light emitting devices as a light source are improved, or the performance of a high density optical memory is improved. Can be realized.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a semiconductor light emitting element and a semiconductor light emitting device of the present invention will be described below with reference to the drawings.

First, the semiconductor light emitting device will be described.

FIG. 1 is a schematic sectional view of a semiconductor light emitting device according to the first embodiment of the present invention. N-GaN low temperature buffer layer 2, n-GaN buffer layer 3, n-In _0.1 Ga _0.9 N buffer layer 4, n-Al _x3 Ga _1-x3 N on sapphire c-plane substrate 1 by metal organic chemical vapor deposition. Clad layer 5, n-GaN optical waveguide layer 6,
In _x1 Ga _1-x1 N / In _x2 Ga _1-x2 N strained multiple quantum well active layer 7
(X1> x2), p-GaN optical waveguide layer 8, p-Al _x3 Ga _1-x3 N first cladding layer 9 and n-Al _x4 Ga _1-x4 N current blocking layer 10 (x4> x
3) to grow sequentially.

A resist is applied on this, and the resist in the stripe region having a width of about 2 μm is removed by using a normal lithography technique, and the remaining resist is used as a mask to dry-etch the n-Al _x4 Ga _{1 -x4} N current block. Remove layer 10.

P-Al _x3 Ga _1-x3 N first cladding layer 9, n-Al _x4 G
The thickness and composition of the a _1-x4 N current blocking layer 10 are set to values that can achieve fundamental transverse mode oscillation (thickness is 1000 to 3000 Å, depending on the oscillation wavelength).

Further, p-Al _x3 Ga _1-x3 N second cladding layer 1
1.Grow p-GaN cap layer 12 and p-SiC contact layer 13 and remove p-SiC contact layer 13 other than the region where the resonator is formed by photolithography and wet and dry etching. Then, by dry etching, the n-GaN buffer layer 3 is partially removed to make contact with the n-side electrode 14. At this time, the cavity surface of the laser is formed.

Subsequently, the n-side electrode 14 and the p-side electrode 15 are formed by ordinary lithography and vapor deposition.

Next, FIG. 2 shows a schematic sectional view of a semiconductor light emitting device according to a second embodiment of the present invention. By p-SiC c-plane substrate 21, p-GaN low temperature buffer layer 22,
p-GaN buffer layer 23, p-In _0.1 Ga _0.9 N buffer layer 24, p-
Al _x3 Ga _1-x3 N cladding layer 25, p-GaN optical waveguide layer 26, In _x1 Ga
_1-x1 N / In _x2 Ga _1-x2 N strained multiple quantum well active layer 27 (x1> x
2), n-GaN optical waveguide layer 28, n-Al _x3 Ga _1-x3 N first cladding layer 29 and p-Al _x4 Ga _1-x4 N current blocking layer 30 (x4> x3) are sequentially grown.

A resist is applied on this, and the resist in the stripe region having a width of about 2 μm is removed by using a normal lithography technique, and the remaining resist is used as a mask to dry-etch the p-Al _x4 Ga _{1 -x4} N current block. Remove layer 30.

N-Al _x3 Ga _1-x3 N first cladding layer 29, p-Al _x4
The thickness and composition of the Ga _{1-x 4} N current blocking layer 30 are set to values at which fundamental transverse mode oscillation can be achieved (thickness is 1000 to 3000 Å, depending on the oscillation wavelength).

Further, the n-Al _x3 Ga _1-x3 N second cladding layer 3
1. An n-GaN contact layer 32 is grown, and a laser cavity surface is formed by ordinary lithography and dry etching or cleavage. Subsequently, the n-side electrode 33 and the p-side electrode 34
To form

Although the p-type layer is grown first in the above structure, the n-side layer may be grown first and p-SiC may be grown as a contact layer.

In the above first and second embodiments,
In _x1 Ga _1-x1 N / In _x2 Ga _1-x2 N strained multiple quantum well active layer is used as the active layer, but Al _y Ga _1-y N / In _z Ga _1-z N (0 ≦ y ≦
It may be a single or multiple strained quantum well active layer of 1,0 ≦ z ≦ 1).

In the above embodiment, since the stripe width of the laser is about 2 μm, the optical output is only about 100 mW. However, it is possible to increase the optical output by expanding the optical waveguide in a taper shape in the same configuration as described above. A semiconductor light emitting device having this tapered stripe structure will be described below as a third embodiment of the present invention with reference to FIG.

FIG. 3A is a schematic sectional view of the semiconductor light emitting device, and FIG. 3B is a schematic top view of the semiconductor light emitting device. By p-SiC c-plane substrate 41, p-GaN low-temperature buffer layer 42, p-GaN buffer layer 43, p-
In _0.1 Ga _0.9 N buffer layer 44, p-Al _x3 Ga _1-x3 N clad layer
45, p-GaN optical waveguide layer 46, In _x1 Ga _1-x1 N / In _x2 Ga _1-x2 N strained multiple quantum well active layer 47 (x1> x2), n-GaN optical waveguide layer 48,
n-Al _x3 Ga _1-x3 N First cladding layer 49 and p-Al _x4 Ga _1-x4 N
The current blocking layer 50 (x4 ≧ x3) is sequentially grown.

A resist is applied on this, and the resist of the stripe region 57 which spreads toward the other end toward the other end with a taper angle of about 6 ° with a minimum width of about 3 μm on one end face is removed by using a normal lithography technique. , P-Al _x4 Ga by dry etching using the remaining resist as a mask
Remove the _1-x4 N current blocking layer 50.

N-Al _x3 Ga _1-x3 N first cladding layer 49, p-Al _x4
The thickness and composition of the Ga _{1-x 4} N current blocking layer 50 are set to values that cannot achieve index guiding.

Further, the n-Al _x3 Ga _1-x3 N second cladding layer 5
1. An n-GaN contact layer 52 is grown, and a laser cavity surface is formed by ordinary lithography and dry etching or cleavage.

Subsequently, an n-side electrode 53 and a p-side electrode 54 are formed. Although the p-type layer is grown first in the above structure, the n-type layer may be grown first and p-SiC may be grown as a contact layer.

In the third embodiment described above, the structure without refractive index guiding has been described, but the structure with refractive index guiding can also be used.

Furthermore, various end face coatings are applied to the resonator surface of the semiconductor light emitting device 60 of the third embodiment,
A high-power semiconductor light emitting device with Gaussian beam quality can be realized.

For example, as shown in FIG. 3 (b), the reflectance of one cross section of the resonator surface of the semiconductor light emitting device of the third embodiment is changed.
A high output single mode semiconductor laser or super luminescence diode or the like can be formed by applying a high reflection coating 55 of 90% or more and a low reflection coating 56 of a reflectance of 1% or less on the emission side end face. .

A specific embodiment of the semiconductor light emitting device will be described below. In the following, the light emitting element is the semiconductor light emitting element 60 of the above-described third embodiment of the present invention.

FIG. 4 shows a first embodiment of the light emitting device. The light emitting element 60 has anti-reflection coatings 61 and 62 on both end surfaces, and a second harmonic generation unit 66 that generates a second harmonic incident on the light emitting element 60. The second harmonic generation unit 66 includes a second harmonic generation element 63 and a lens 65 that causes the light from the second harmonic generation element 63 to enter the light emitting element 60. The semiconductor light emitting element 60 acts as an optical amplifier for amplifying the second harmonic wave incident from the second harmonic wave generating element 63 through the lens 65. At this time, it is possible to efficiently amplify the high-quality short-wavelength laser light from the second harmonic generation unit having the wavelength conversion element having excellent wavelength purity and lateral mode controllability.

FIG. 5 shows a second embodiment of the light emitting device. This semiconductor light emitting device has a light emitting element 60 in which a low reflection coating 71 of about 0.5% is provided on the light emitting side and an antireflection coating 72 is provided on the opposite side, and the wavelength of incident light is selectively selected. And a wavelength selection unit 76 that reflects light. Specifically, the wavelength selection unit 76 includes a grating 73 arranged on the non-reflection coating 72 side of the light emitting element 60 and a grating 73 for emitting light from the light emitting element 60.
And a lens 74 for making the wavelength-selected light from the grating 73 enter the light emitting element 60. The light from the antireflection coat 72 surface of the light emitting element 60 is wavelength-selected by the grating 73, and the wavelength-selected light is returned to the antireflection coat 72 surface of the light emitting element 60. This makes it possible to emit a single-mode high-power laser beam.

FIG. 6 shows a third embodiment of the light emitting device. This semiconductor light emitting device includes a light emitting element 60 having a low reflection coating 81 of about 0.5% on the light emitting side and an antireflection coating 82 on the opposite side, and a wavelength of incident light selectively. The wavelength selection unit 86 that reflects light is included. The wavelength selection unit 86 is disposed on the non-reflection coating 82 side of the light emitting device 60 and the light emitting device 60.
The light from the mirror 83, the filter 84 that selectively transmits the wavelength of the light reflected by the mirror 83, the light from the light-emitting element 84 is incident on the mirror 83, and the wavelength is selected by the filter 84. And a lens 85 that allows light to enter the light emitting element 60. Non-reflective coating 82 of the light emitting device 60
The light from the surface is reflected by the mirror 83, the reflected light is wavelength-selected in the filter 84, and the wavelength-selected light is returned to the surface of the non-reflection coat 82 of the light emitting element 60. As a result, a single mode high power semiconductor laser beam can be emitted.

The semiconductor light emitting element and the semiconductor light emitting device of the present invention are used for high speed information / image processing, communication, measurement,
It can be applied as a light source in the fields of medicine and printing.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a semiconductor light emitting device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a semiconductor light emitting device according to a second embodiment of the present invention.

FIG. 3 is a sectional view (a) and a top view (b) of a semiconductor light emitting device according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram when the semiconductor light emitting device of the present invention is used as an optical amplifier for SHG light.

FIG. 5 is a schematic configuration diagram in which a single mode high power semiconductor laser is formed using the semiconductor light emitting device of the present invention.

FIG. 6 is a schematic configuration diagram in which a single-mode high-power semiconductor laser is formed by combining the semiconductor light emitting device of the present invention and a mirror.

[Explanation of symbols]

1 sapphire c-plane substrate 2 n-GaN low temperature buffer layer 3 n-GaN buffer layer 4 n-In _0.1 Ga _0.9 N buffer layer 5 n-Al _x3 Ga _1-x3 N clad layer 6 n-GaN optical waveguide layer 7 In _x1 Ga _1-x1 N / In _x2 Ga _1-x2 N strained multiple quantum well active layer (x1> x2) 8 p-GaN optical waveguide layer 9 p-Al _x3 Ga _1-x3 N first cladding layer 10 n-Al _x4 Ga _1-x4 N Current confinement layer (x4> x3) 11 p-Al _x3 Ga _1-x3 N Second clad layer 12 p-GaN cap layer 13 p-SiC contact layer 14 n-side electrode 15 p-side electrode

Claims (9)

[Claims] 1. An AlInGaN-based semiconductor light-emitting device comprising at least a first-conductivity-type cladding layer, an active layer, and a second-conductivity-type first cladding layer laminated in this order on a substrate, wherein the second-conductivity-type first cladding A first conductivity type current blocking layer having a stripe-shaped current injection window is laminated on the layer, and a second conductivity type second clad layer and a second conductivity type are provided on the current blocking layer so as to cover the current injection window. Type contact layers are stacked in this order to form an internal current constriction mechanism, and a resonator surface is formed on two opposite end faces parallel to the stacking direction, on the second conductivity type contact layer and on the substrate side. An AlInGaN-based semiconductor light-emitting device, characterized in that electrodes are formed on each. 2. The first conductivity type and the second conductivity type are n-type and p-type, respectively, and the second conductivity type contact layer is a p-SiC semiconductor layer. AlInGaN-based semiconductor light emitting device. 3. The AlInGaN-based semiconductor light emitting device according to claim 1, wherein the first conductivity type and the second conductivity type are p-type and n-type, respectively, and the substrate is a p-SiC semiconductor. 4. The refractive index step is provided in a joint surface between the first and second clad layers of the second conductivity type and the current blocking layer of the first conductivity type. The AlInGaN-based semiconductor light-emitting device according to any one of the above. 5. The stripe-shaped current injection window is tapered from one end surface to the other end surface of the resonator.
AlInGaN-based semiconductor light emitting device. 6. A semiconductor light emitting device comprising the AlInGaN based semiconductor light emitting element according to claim 5, wherein the two end faces of the resonator are provided with a predetermined reflectance coating. 7. Of the two end faces, the predetermined reflectance coat applied to the one end face is a high reflectance coat of 90% or more, and the predetermined reflectance coat applied to the other end face is 1% or less. 7. The semiconductor light emitting device according to claim 6, which is a low reflection coat of 8. The predetermined reflectance coat applied to the two end faces is a non-reflection coat, and the second harmonic generation unit for generating the second harmonic incident on the semiconductor light emitting device is the semiconductor light emitting device. 7. The semiconductor light emitting device according to claim 6, wherein the semiconductor light emitting element is arranged on the one end face side of the element, and the semiconductor light emitting element amplifies and emits the second harmonic wave incident from the second harmonic wave generating section. . 9. The predetermined reflectance coat applied to the one end face of the two end faces is a non-reflection coat, and the predetermined reflectance coat applied to the other end face is a low reflectance of 1% or less. It is a reflective coat, and the wavelength selection part that selects and reflects the wavelength of the incident light is
The semiconductor light emitting device is arranged on the one end face side on which the non-reflection coating is applied, and the wavelength selection unit performs wavelength selection of light emitted from the one end face of the semiconductor light emitting device,
7. The semiconductor light emitting device according to claim 6, wherein the selected light is returned to the one end surface to emit a single mode laser.