JP2001148511A - Semiconductor light-emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-luminance semiconductor LED, that preferentially and uniformly diffuses element drive current into an open light-emitting region in a semiconductor LED with a pedestal electrode and a window layer. SOLUTION: A conductive electrode is provided between a light-emitting part and a window layer, where the conductive electrode has an extraction hole part in an open light-emitting region, and is machined into a net shape.

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 diode, and more particularly, to a semiconductor light emitting diode for diffusing an LED driving current supplied from a connection pedestal electrode to a light emitting portion region through a window layer. The present invention relates to a configuration of an electrode.

[0002]

2. Description of the Related Art Indium tin oxide (abbreviation: ITO)
Having a window layer made of a conductive oxide material such as III-
Group V compound semiconductor light emitting diode (LED)
The LED drive current is supplied from a pedestal (pad) electrode solely disposed on the upper surface of the window layer. However, the oxide layer constituting the window layer and the III constituting the LED
If the structure is directly joined to the -V group compound semiconductor layer, a high junction barrier is formed, and the drive current cannot be widely diffused to the light emitting portion. Therefore, a very high forward voltage (so-called V
f) results. For example, gallium nitride (chemical formula: G
aN) with a structure in which ITO is bonded as a transparent window layer, the Vf (forward current = 20 mA) of a GaN-based LED exceeds 7 volts (unit: V) which is about twice the general value (Appl. Phys.Lett., 74 (26).
(1999), p. 3930-3932). this is,
This hinders obtaining a high-brightness GaN-based LED having a transparent conductive window layer that can be driven at a low voltage.

An aluminum-gallium-indium phosphide mixed crystal ((Al _x Ga _{1 -x} ) _0.5 In _0.5 P (0 ≦ X ≦ 1)) which is substantially lattice-matched with gallium arsenide (chemical formula: GaAs)
In the case of an AlGaInP-based LED having a light emitting layer, only a window is provided on the upper surface of a transparent oxide window layer made of ITO in order to efficiently drive a drive current supplied from a pedestal electrode provided to a light emitting portion. A configuration in which a contact layer is disposed between a layer and an LED constituent layer is known (see Japanese Patent Application Laid-Open No. H11-17220). The contact layer is provided to promote ohmic contact between the window layer and the III-V compound semiconductor layer constituting the LED, and is made of GaAs, gallium arsenide phosphide (composition formula: Ga).
_{As 1-C P C: 0} ≦ C ≦ 1) has a those composed of the like (see JP-A of JP-A 11-17220).
However, in the conventional group III-V compound semiconductor LED,
Making the band gap narrower than corresponding to the emission wavelength III-
Since a contact layer made of a group V compound semiconductor is laid so as to cover the surface of the light emitting region (see Japanese Patent Application Laid-Open No.
In this configuration, light emission is absorbed by the contact layer, which hinders obtaining a high-brightness III-V compound semiconductor LED.

In the invention described in Japanese Patent Application Laid-Open No. 11-4020, zinc (element symbol: between the ITO transparent electrode layer on which the pedestal electrode for bonding is laid only on the upper surface and the LED constituting layer. AlG having a metal film such as Zn)
An aInPLED is disclosed. According to this conventional technique, a metal film of Zn or the like is uniformly arranged over the entire light emitting region for the purpose of enhancing the adhesion between the ITO electrode layer and the III-V compound semiconductor constituent layer. It has a configuration.
In such a method in which a continuous film made of a metal material is disposed immediately below the ITO transparent electrode layer, light emitted from the light emitting layer is relentlessly absorbed by the metal material film.
It is a hindrance to obtaining InPLED.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a structure of an element which can efficiently extract light emitted from a light emitting portion to the outside and can diffuse a drive current widely in a light emitting portion region. The purpose is.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention. That is, the present invention provides [1] a semiconductor light-emitting diode having a light-emitting layer, a window layer, and a pedestal electrode for connection, wherein the semiconductor light-emitting diode has a mesh-shaped conductive electrode other than a projection region of the pedestal electrode on an element plane. Light emitting diode,
[2] The planar shape of the element has a side length of 150 to 500.
The semiconductor light-emitting diode according to [1], which is substantially square in μm, and [3] a mesh-shaped conductive electrode is laid on substantially the entire surface of the element plane other than the projection region of the pedestal electrode. [1] or [2]
[4] wherein the shape of the mesh-shaped conductive electrode in the element plane is point-symmetric with respect to the center point of the projection area of the pedestal electrode [1] to [3]. The semiconductor light-emitting diode according to any one of [1] to [5], wherein the shape of the mesh-shaped conductive electrode in the element plane is line-symmetric with respect to a line passing through the center point of the projection region of the pedestal electrode. The semiconductor light-emitting diode according to any one of [1] to [4], wherein the light-emitting layer is formed from a III-V compound semiconductor. [7] The semiconductor light emitting diode according to any one of [1] to [6], wherein the window layer includes a layer formed from an oxide. [8] the mesh-shaped conductive electrode is made of metal The semiconductor diode according to any one of [1] to [7], wherein [9] the total area of the mesh-shaped conductive electrodes on the element plane is equal to the pedestal electrode. Any one of [1] to [8], which is within a range of 10 to 500% of the bottom area.
Item [10] In the element plane, the area of the portion excluding the mesh-shaped conductive electrode and the bottom of the pedestal electrode is 30 to 9 in terms of the area ratio to the entire element plane.
The light emitting diode according to any one of [1] to [9], wherein the shape of the mesh-shaped conductive electrode in the element plane is 5 to 200 μm in diameter.
The semiconductor light-emitting diode according to any one of [1] to [10], wherein the semiconductor light-emitting diode according to any one of [1] to [10], wherein [12] a mesh-shaped conductive electrode in the element plane is included in a range of m. The semiconductor light-emitting diode according to any one of [1] to [11], wherein the shape includes an elliptical hole formed in a range of 5 to 200 μm in major axis, [13] mesh-like shape. The shape according to any one of [1] to [12], wherein the shape of the conductive electrode in the element plane includes a region which has a rectangular shape with a side length of 5 to 200 μm. The semiconductor light emitting diode, [14] the shape of the mesh-shaped conductive electrode in the element plane is 5 to 200
The semiconductor light-emitting diode according to any one of [1] to [13], including a region pierced into a polygon in a range of μm, [15] an element plane of a mesh-like conductive electrode. Is characterized by including a band-shaped region with a width of 5 to 100 μm [1] to [14].
A semiconductor light-emitting diode according to any one of the above.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor LED according to the present invention comprises:
It has a light-emitting layer, a window layer, and a pedestal electrode for connection, and has a mesh-shaped conductive electrode in a region other than the projection region of the pedestal electrode on the element plane. Particularly, the semiconductor LED having the structure of the present invention includes aluminum gallium arsenide (composition formula: Al _X Ga _{1 -X} As: 0 ≦ X ≦ 1), gallium arsenide phosphide (composition formula: GaAs _1-X P _X ), (Al _X Ga _1-X ) _Y I
n _1-Y P and aluminum gallium indium nitride (composition formula: Al _X Ga _Y In _1-XY N: 0 ≦ X, Y ≦ 1,
When the light-emitting layer (light-emitting portion) is made of a group III-V compound composed of (X + Y = 1), a preferable effect can be obtained. The group III-V compound semiconductor crystal layer constituting the light emitting portion is formed by a metal organic chemical vapor deposition (MOCVD) method, a molecular beam epitaxial growth method (MBE method), a halogen (halo).
n) or a film can be formed by epitaxial growth means such as hydride vapor phase epitaxy. FIG. 1 is a schematic plan view of a group III-V compound semiconductor LED 10 for conceptually explaining a first embodiment according to claim 1 of the present invention. FIG. 2 shows the LED shown in FIG.
It is sectional schematic along the broken line XY of 10.

Referring to FIG. 2, an LED 10 according to the present invention is an n-type or p-type LED made of a group III-V compound semiconductor layer laminated on a surface of a substrate 101 made of a single crystal by an epitaxial growth method. Clad
d) Hetero (he) between the layers 104 and 106 and the light emitting layer 105
tero) a light emitting unit 10a formed of a junction;
It basically has a window layer 108 crowned thereon. A structure in which a Bragg reflection (DBR) 103 is inserted between the light emitting layer 104 and the buffer layer 102 may be used. A pedestal electrode 109 for supplying an LED drive current is provided at the center of the upper surface of the window layer 108. The LED 10 according to the present invention is characterized in that a net-like conductive material having an opening formed in the open light emitting region 106 a on the surface of the group III-V compound semiconductor layer 106 joined to the transparent oxide layer forming the window layer 108. That is, the sex electrode 107 is laid. The open light emitting area surface 106a is an area where light emitted from the light emitting layer 104 can be extracted to the outside without being shielded. That is, the outer peripheral region of the region on the window layer 108 where the pedestal electrode 109 is laid, or the pedestal electrode 10
The area other than the projection area 109a of FIG.
a. Note that the effect of the present invention can be obtained even if the reticulated conductive electrode 107 of the present invention is provided in the projection region 109a of the pedestal electrode 109. In this case, Vf can be further reduced, but the luminous efficiency is slightly reduced because the diffusion current to the portion where light emission is blocked by the pedestal electrode increases.

Further, a further feature of the present invention is that a conductive electrode (ohmic electrode) 10 provided in the open light emitting region 106a is provided.
7 consists of a mesh-like membrane which is squeezed and has an opening. The semiconductor layer constituting the LED is exposed in the opening. For example, FIG.
And the LED 10 illustrated in FIG.
The upper clad layer 106 forming a is exposed at the opening. Conductive electrode 107 laid in open light emitting area 106a
Is constituted by a mesh-like ohmic electrode 107 having an opening, light emitted through the opening is led out without being shielded. Therefore, there is an advantage that a sudden decrease in the plane area of the open light emitting region 106a can be avoided. The preferred chip size (indicated by the symbol Q in FIG. 1) of the semiconductor LED used in the present invention is approximately square in the range of 150 to 500 μm, more preferably 180 to 300 μm, and the preferred size of the pedestal electrode is the bottom surface. It is in the range of 80 to 160 μm in terms of diameter when the shape is circular. A substantially square means that the ratio of one side to the other side is preferably 0.8
It is a rectangle or square that is 〜1.2. In addition, in the opening of the conductive electrode, the preferred shape of the opening is a circle, an ellipse, a square, a polygon, a band, and the size of each is a circular diameter, an elliptical long diameter, and a rectangular shape. The length of one side, preferably the length of one side of the polygon is 5 to 200 μm,
More preferably 5 to 50 μm, most preferably 5 to 30 μm
μm, and in the case where the openings are strip-shaped, the width is preferably 5 to 100 μm, more preferably 5 to 50 μm, and most preferably 5 to 30 μm.

The total area of the mesh-shaped conductive electrodes on the element plane (excluding the portion where the bottoms of the conductive electrode and the pedestal electrode overlap on the element plane) is the ratio to the bottom area of the pedestal electrode. And preferably 10 to 500
%, More preferably 20-250%, most preferably 3%
In the range of 0 to 150%, the area of the portion excluding the mesh-shaped conductive electrode and the bottom of the pedestal electrode on the element plane is preferably 3% of the entire element plane.
By setting the range of 0 to 95%, more preferably 35 to 90%, and most preferably 40 to 80%, it becomes possible to reduce Vf and improve luminous efficiency.

The conductive electrode 107 is made of aluminum (A
i), nickel (element symbol: Ni) or the like, but a structure including a layer formed of a gold (Au) alloy is preferable because the current supplied from the pedestal electrode can be efficiently diffused into the light emitting layer. . Among them, for the n-type semiconductor constituent layer, a gold (element symbol: Au) -germanium (element symbol: Ge) alloy, gold-indium (element symbol: I)
An electrode having excellent ohmic contact can be formed by using an n) alloy or a gold alloy such as a gold-tin (element symbol: Sn) alloy. For the p-type semiconductor layer, an electrode having excellent ohmic contact is provided from a gold-zinc (element symbol: Zn) alloy or a gold-beryllium (element symbol: Be) alloy. In the mesh electrode according to the present invention, the portions other than the opening (the squeezed portion) are connected to each other, and electrical continuity is secured at the connection. Therefore, a mesh electrode having an ohmic contact and exhibiting electrical continuity and having excellent ohmic contact is provided in the open light emitting region 10 while having an opening for transmitting light emission.
According to the means for laying almost on the entire surface of the pedestal electrode 109,
The drive current supplied via the conductive transparent oxide window layer 108 can be more efficiently circulated to the light emitting unit 10a. In order to obtain good LED drive current flow, it is necessary to reduce the flow resistance by increasing the thickness of the reticulated film forming the conductive electrode 107. The thickness of the mesh electrode film required to obtain a low resistance capable of diffusing the drive current over substantially the entire open light emitting region 106a is 5 nanometers (unit: nm) or more. When the reticulated metal film is extremely thick, the step between the III-V compound semiconductor constituent layer and the reticulated metal film becomes large, and in the case of forming a window layer described later, there arises a problem that the periphery of the reticulated film cannot be sufficiently covered. . For this reason, it is desirable that the thickness of the film forming the mesh electrode be 600 nm or less.

In order to make the electric field distribution in the open light emitting region 106a more uniform, the shape of the opening (hole) in the reticulated film forming the conductive electrode 107 in the element plane is the pedestal electrode 109 (the pedestal electrode). It is desirable that the projection areas 109a) are arranged point-symmetrically with respect to the center point M of the projection area 109a, or line-symmetrically with any of the center lines C1 and C2 passing through the center point M. Further, it is desirable to provide a plurality of the above-mentioned openings. In addition, it is convenient to arrange the openings at equal intervals (= d) in the open light emitting region 106a in order to form a uniform electric field intensity distribution in the open light emitting region 106a. Furthermore, equidistant (= R) from the center point M of the planar shape of the pedestal electrode 109 (projection region 109a of the pedestal electrode).
It is more convenient to arrange them at equal intervals (= d) while maintaining the following. A uniform electric field intensity distribution can contribute to providing uniform intensity light emission in the open light emitting region 106a. Further, when the interval between the holes is extremely reduced, that is, when the interval between the adjacent holes is extremely small and the width of the connecting portion of the metal film is reduced, the flow of the operating current is reduced. The resistance increases, and there arises a problem that the operating current cannot be sufficiently diffused over the entire open light emitting region 106a. In addition, for example, if the interval is as small as 5 μm or less, the probability that the metal connection portion between the squeezed portions breaks during micromachining increases, and a case where diffusion of the operating current over a wide range may not be achieved constantly occurs. I do.

The window layer 108 covering the conductive electrode 107 is Ga
Although it can be composed of P, AlGaAs, metal oxide, or the like, it is particularly preferable to have a constitution including a layer formed of an oxide. In this case, indium oxide (In ₂ oxide) is preferable.
O ₃ ), tin oxide (SnO ₂ ), indium tin oxide (IT
It is particularly preferable to use a conductive transparent oxide material such as O). Aluminum (element symbol: Al),
Zinc oxide (chemical formula: ZnO), which is doped with gallium (element symbol: Ga) or indium (element symbol: In) and has a low resistivity, can also be suitably used. In order to allow the LED driving current supplied from the pedestal electrode 109 provided on the upper surface to flow through the mesh-like conductive electrode 107, the window layer 108 is about 1 × 10 ⁻³ ohm-cm (Ω · cm) or less, preferably It is made of a material having a low resistivity of about 5 × 10 ⁻⁴ Ω · cm. The window layer 108 needs to have an effect to sufficiently take out short-wavelength light such as near-ultraviolet light, blue light, or green light emitted from the III-V compound semiconductor light-emitting layer to the outside. It is preferable to use a material having a band gap of approximately 3 electron volts (unit: eV) or more. Incidentally, the band gap of ITO and zinc oxide at room temperature is about 3.4 to 3.5 eV. Window layer 10
The thickness of the conductive oxide layer constituting 8 is set to a thickness that gives a high transmittance to the emission wavelength.

The pedestal electrode 10 provided on the upper surface of the window layer 108
The plane shape of 9 can be a polygon such as a regular hexagon or a regular octagon in addition to a general circle, an ellipse, or a square such as a square or a rectangle. Whichever planar shape is selected, the planar shape of the pedestal electrode 109 is desirably bilaterally symmetric so as to provide an open light-emitting region 106a that is bilaterally symmetric. In addition, the pedestal electrode 10 of any planar shape
9 so that the connection can be easily achieved and the surface area of the open light emitting region 106a is not reduced unnecessarily.
The diameter of a circular pedestal electrode, the major axis of an elliptical pedestal electrode, the length of one side of a square pedestal electrode, the length of a short side of a rectangular pedestal electrode, and the length of a diagonal line of a polygonal pedestal electrode are at least about 80 to 160 μm. It is desirable to be within the range.

On the other hand, the above-mentioned conductive electrode 1 made of a reticulated film
Another conductive electrode 110 whose polarity is opposite to that of 07 is provided on the back surface of the substrate 101 when the substrate 101 to be used is an n-type or p-type conductive crystal. The conductive electrode 110 laid on the back surface of the substrate 101 is generally provided over substantially the entire surface of the back surface of the substrate. In the case of a non-conductive or insulating substrate 101, the conductive electrode 110 is an n-type or p-type conductive I
It is generally laid on a part of the II-V compound semiconductor constituent layer.

An eleventh embodiment according to the eleventh aspect of the present invention is characterized in that the conductive electrode is constituted by a mesh-like electrode including a circular hole. FIG. 3 illustrates a schematic plan view of a III-V compound semiconductor LED 20 including the conductive electrode 107 according to the present embodiment. The circular hole 111 has a circular pedestal electrode 109 (the pedestal electrode 10).
Nine projection areas 109a) are provided at positions that are line-symmetric with respect to the center lines C1 and C2 (diagonal lines L1 and L2) passing through the center point M of the planar shape. In other words, the circular hole 111 is an opening, and is a region where the group III-V compound semiconductor constituent layer immediately below is exposed. Therefore, the configuration does not block light emitted from the light emitting unit. In the reticulated electrode illustrated in FIG. 3, all the holes have circular shapes having the same diameter, but it is not necessary that all the holes have the same planar shape. For example, the conductive electrode can also be formed from a mesh electrode in which the hole near the center of the LED around the pedestal electrode is circular and the hole near the periphery of the LED is elliptical. Even if the plane shape or the hole area (opening area) of the hole portion is changed depending on the region in the open light emitting region, the resulting reticulated electrode is the center line (C1, C2) or the diagonal line (L1, L2). Is optimally symmetric with respect to. Open light emitting area 106a
This is to make the potential distribution in the first embodiment uniform.

According to a twelfth embodiment of the present invention, the conductive electrode is constituted by a mesh electrode including an elliptical hole. By making the plane shape of the hole portion circular as described in the tenth embodiment or by making it elliptical as in the present embodiment, a net-like electrode having a symmetrical shape can be easily provided. It is. FIG. 4 shows an elliptical hole 112 according to this embodiment.
1 schematically shows a planar structure of a group III-V compound semiconductor LED 30 provided with a conductive electrode 107 having: The elliptical hole 112 has a conductive electrode 107 whose major axis 112a is parallel to any of the center lines C1 and C2 or the diagonal lines L1 and L2 of the LED 30. However, it can also be constituted by a mesh electrode having a circular hole and an elliptical hole.

According to a thirteenth embodiment of the present invention, the conductive electrode is constituted by a mesh-like electrode including a region 113 which has been squarely bored. FIG. 5 is a schematic plan view of a group III-V compound semiconductor LED 40 including the conductive electrode 107 according to the present embodiment. Although the conductive electrode 107 illustrated in FIG. 4 is formed of a reticulated metal film formed into a square, the hole may be rectangular. The conductive electrode can also be formed from a reticulated membrane having square and rectangular holes. When an opening having a different shape is provided, the shape and position of the opening are provided so as to be line-symmetric with respect to the center lines C1, C2 or the diagonal lines L1, L2. This is for forming a uniform potential distribution in the open light emitting region 106a. Since the light emission in the projection region 109a of the pedestal electrode is shielded by the pedestal electrode 109 and cannot be extracted to the outside, the improvement of the luminescence intensity can hardly be achieved when the operating current is passed immediately below the pedestal electrode 109. As in the present invention, by disposing a conductive electrode limited to the open light emitting region 106a and having a shape through which an operation current can flow preferentially, it can diffuse over substantially the entire open light emitting region 106a and have a high light emission intensity.
This is advantageous for obtaining a group V compound semiconductor LED.

According to a fourteenth embodiment of the present invention, the conductive electrode is constituted by a mesh-like electrode including a polygonally punched region. In particular, it is preferable that the shape of the hole is a bilaterally symmetric polygon such as a regular hexagon or regular octagon in order to obtain a net-like electrode having a symmetrical planar shape. FIG.
An LED 50 having a conductive electrode 107 having a regular hexagonal hole 114 according to the present embodiment will be exemplified. Since the region other than the region pierced in the polygonal shape is a connecting portion, the operating current is supplied to the open light emitting region 106 a
Can be evenly and uniformly diffused over substantially the entire area. FIG. 7 shows an open light emitting area 106a other than the projection area 109a of the pedestal electrode 109, a regular hexagonal hole 114 in a peripheral area of the projection area 109a, and a circular area around the open light emitting area 106a. 2 schematically illustrates a planar configuration of the LED 60 provided with the conductive electrode 107 formed of a reticulated film provided with 111. In the projection region 109a located immediately below the pedestal electrode 109, the window layer 108 and the semiconductor constituent layer are in direct contact with each other, forming a high junction barrier. For this reason, the LED operating current supplied from the pedestal electrode 109 is larger than the projection area 109a of the pedestal electrode in the open light emitting area 106a.
Can be distributed preferentially. Therefore, the efficiency of external emission of light can be improved, and a semiconductor LED with high light emission intensity can be obtained.

According to a fifteenth embodiment of the present invention, the conductive electrode is constituted by a mesh electrode including a band-shaped hole. It is preferable that the strip-shaped hole 115 is disposed in parallel with the center lines C1, C2 or the diagonal lines L1, L2 of the LED. FIG. 8 shows an LED 70 having a reticulated electrode formed in a strip along a direction parallel to the center line C1.
Is exemplified. The LED 80 shown in the schematic plan view of FIG.
Is a band-shaped hole 1 provided in parallel with both center lines C1 and C2.
15 is provided. FIG. 10 shows a band-shaped hole 1 parallel to the center lines C1 and C2.
15 illustrates an LED 90 including a conductive electrode 107 having an opening formed by combining the vertical and horizontal lines 15. Regardless of the plane shape, it is necessary to form a connected metal film except for the hole. This is to diffuse the LED driving current widely over the entire open light emitting region 106a.

[0021]

EXAMPLES (Example 1) Hereinafter, the present invention will be described in detail based on examples. FIG. 11 shows the AlGaI according to this embodiment.
1 shows a schematic plan view of an nP LED 100. FIG. FIG.
FIG. 12 is a schematic cross-sectional view of the LED 100 shown in FIG. 11 taken along a broken line AA ′.

The LED 100 has a Zn (Zn) -doped p-type (001) -GaAs single crystal circular substrate 201 having a diameter of about 50 mm, and is sequentially stacked on a Zn-doped p-type GaAs.
Buffer layer 202, both p-type Al doped with Zn
_0.40 Ga _0.60 As layer Bragg reflector consisting of 12 layers stacked periodic structure alternately and p-type Al _{0. 95} Ga _0.05 As layer (DBR) layer 203, Zn-doped p-type (Al _0.7 G
a _0.3 ) a lower cladding layer 204 made of _0.5 In _0.5 P;
A light-emitting layer 205 composed of an undoped n-type (Al _0.2 Ga _0.8 ) _0.5 In _0.5 P mixed crystal, and a Si-doped n-type (Al _0.7
An upper cladding layer 206 made of Ga _{0.3) 0.5} In _0.5 P
Laminated structure (wafer) 1 composed of
A was configured as a base material.

Each constituent layer 202 constituting the laminated structure 1A
To 206 are trimethyl aluminum ((CH ₃ ) ₃ A)
l), trimethylgallium ((CH ₃ ) ₃ Ga) and trimethyl indium ((CH ₃ ) ₃ In) were formed by a low-pressure MOCVD method using a group III constituent element as a raw material. Diethyl zinc ((C ₂ H ₅ )) is used as a zinc (Zn) doping source.
₂ Zn) was used. Disilane (Si ₂ H ₆ ) was used as a silicon (Si) dopant source. Each constituent layer 202-2
The film forming temperature of No. 06 was unified to 730 ° C. The carrier concentration of the buffer layer 202 was about 5 × 10 ¹⁸ cm ⁻³ , and the layer thickness was about 1 μm. N-type Al _0.40 Ga forming the DBR layer 203
The thickness of each of the _0.60 As layer and the n-type Al _0.95 Ga _0.05 As layer was about 40 nm. Each carrier concentration is about 1 × 1
0 ¹⁸ cm ⁻³ . The lower cladding layer 204 has a carrier concentration of about 3 × 10 ¹⁸ cm ⁻³ and a thickness of about 1.5 μm.
And The thickness of the light emitting layer 205 was about 15 nm, and the carrier concentration was about 5 × 10 ¹⁶ cm ⁻³ . The carrier concentration of the n-type upper cladding layer 206 was about 2 × 10 ¹⁸ cm ^−3, and the layer thickness was about 5 μm.

A gold-germanium alloy (Au 95% by weight-Ge 5% by weight) having a thickness of about 50 nm is formed on the entire surface of the n-type upper cladding layer 206 by a general vacuum deposition method.
Alloy) film was deposited. Subsequently, a gold (Au) film having a thickness of about 50 nm was applied on the surface of the Au-Ge alloy film. Next, the Au—Ge / Au multilayer film is patterned by using general photolithography means, and the first and second arc-shaped holes 207a and 207b are formed.
And a conductive electrode 20 in which a circular hole 207c coexists
7 was formed. The first arc-shaped hole 207a was provided on the circumference of the projection area 209a of the pedestal electrode 209 having a diameter of 180 μm centered on the center M of the planar shape. The first arc-shaped holes 207a are arranged symmetrically with respect to both center lines C1 and C2 of the LED 100. The width of the first arc-shaped hole 207a was about 50 μm, and the length of the arc along the circumference of the first arc 207a was about 95 μm. The second arc-shaped holes 207b were provided at a total of four places on a circumference of 220 μm in diameter centered on the center M of the projection region 209a of the pedestal electrode. The second arc-shaped hole 207b is the LED 10
They are arranged so as to be bilaterally symmetrical with respect to both diagonal lines C1 and C2 of 0. The width of the second arc-shaped hole 207b is about 60 μm.
m, and the length of the circular arc was about 115 μm. A circular hole 207 having a diameter of 30 μm is provided between the second arc-shaped hole 207b and the outer edge 100b of the LED 100.
c was provided. The circular hole 207c is provided at the center on both diagonal lines C1 and C2 of the LED 100.

The length of one side of the LED 100 (= Q) is 26
0 μm, and the diameter of the pedestal electrode 209 is 110 μm
Therefore, the surface area of the open light emitting area 206a excluding the projection area 209a of the pedestal electrode was about 5.8 × 10 ⁻⁴ cm ² . In addition, the first and second arc-shaped holes 20
The total area of 7a, 207b and circular hole 207c is about 2.4 × 10 ⁻⁴ cm ² . Therefore, the ratio of the plane area of the squeezed portion to the surface area of the open light emitting region 206a was about 41.3%. In addition, the ratio of the portion excluding the conductive electrode 207 and the bottom of the pedestal electrode 209 on the element plane to the entire element plane was about 50%.

Next, an indium tin oxide (ITO) film serving as a transparent window layer 208 was applied on the surface of the upper cladding layer 206 on which the conductive electrode 207 was disposed by a general magnetron sputtering method. The specific resistance of the ITO layer was about 5 × 10 ⁻⁴ Ω · cm, and the layer thickness was about 600 nm. Next, after a general organic photoresist material was applied to the entire surface of the window layer 208, a region where the pedestal electrode 209 was to be provided was patterned using a known photolithography technique. Thereafter, a gold (Au) film was deposited on the entire surface by a vacuum deposition method while the patterned resist material was left. The thickness of the gold (Au) film is about 700
nm. Thereafter, the well-known lift-off (lift-off) is performed.
By means of off) means, the Au film was left only in the area where the pedestal electrode 209 was to be formed, while the resist material was peeled off. Thus, a circular pedestal electrode 209 having a diameter of about 110 μm was formed. The base area of the pedestal electrode 209 was about 0.95 × 10 ⁻⁴ cm ² . Also, the conductive electrode 20
The ratio of the total area of No. 7 to the bottom area of the pedestal electrode is about 3
It was 58%.

On the back surface of the p-type GaAs single crystal substrate 201, a p-type conductive electrode 21 made of a gold-zinc (Au-Zn) alloy
After forming 0, the laminated structure (wafer) 1A was cut and divided into individual pieces by a normal scribing method to obtain LED chips 100. The chip (individual element) 100 was a square having a side length (= Q) of 260 μm. A current was passed in the forward direction between the n-type conductive electrode 207 via the p-type conductive electrode 210 and the pedestal electrode 209, and red-orange light having a wavelength of about 620 nm was obtained through the open light-emitting region 206a. The half width of the light emission spectrum was about 20 nm, and the light emission was excellent in monochromaticity. Forward voltage (Vf: ＠ 2) when a current of 20 mA (mA) flows
0 mA) was about 2.1 volts (V), reflecting good ohmic characteristics of the conductive electrode 207 made of a reticulated metal film. In addition, since the conductive electrode 207 is formed of a net-like metal film having a hole, light emission is also observed in the area of the peripheral edge 100b of the chip 100, and the measurement is easily performed with the visibility corrected. The intensity of the emitted light was about 74 millicandela (mcd). Further, in the present embodiment, Al
In the GaInP-based LED 100, even from the viewpoint of the near-field light-emitting pattern, the distribution of the light-emitting intensity on the open light-emitting surface 206a became uniform due to the effect of uniform distribution of the operating current by the reticulated conductive electrode 207.

(Embodiment 2) In this embodiment, the present invention will be described in detail by taking as an example a case in which a gallium nitride (GaN) LED having a mesh-shaped conductive electrode formed in a diamond shape is formed. Will be explained. FIG. 13 shows a GaN-based LED 2
00 shows a schematic plan view. FIG. 14 shows L in FIG.
FIG. 3 shows a schematic cross-sectional view of the ED 200 along a broken line BB ′.

Boron (element symbol: B) doped p-type (00
1) On a silicon (Si) single crystal circular substrate 301, zinc (Z
n) doped p-type boron phosphide (BP) low temperature buffer layer 302;
A Zn-doped p-type BP high-temperature buffer layer 303, a lower cladding layer 304 made of p-type GaN doped with magnesium (Mg), an average indium (In) composition ratio of 0.10, and a plurality of indium compositions different from each other. N-type Ga _0.90 In having a multi-phase structure composed of phases
_0.10 N light emitting layer 305, silicon (Si) doped n-type Al _0.15 Ga with an aluminum (Al) composition ratio of 0.15
_An upper cladding layer 306 of _0.85 and Si-doped n
The contact layer 307 made of shaped GaN was sequentially laminated to form a laminated structure 3A for the GaN-based LED 200.

The BP buffer layers 302 and 303 are made of triethyl boron.
Element (chemical formula: (C_TwoH_Five)_ThreeB) and phosphine (P
H_Three) Was formed as a raw material by a reduced pressure MOCVD method.
The BP low-temperature buffer layer 302 is formed at 400 ° C. and has a thickness of about 1
It was set to 0 nm. The BP high temperature buffer layer 303 is formed at 1030 ° C.
The film was formed, and the layer thickness was about 1 μm. Carrier concentration is about 2 × 1
0¹⁸cm^-3And The zinc doping source is diethyl
Lead (chemical formula: (C_TwoH_Five) _TwoZn) was used.

Other components constituting the laminated structure 3A
Layers 304-307 are made of trimethyl aluminum ((C
H_Three)_ThreeAl), trimethylgallium ((CH_Three)_ThreeGa)
And trimethylindium ((CH_Three)_ThreeIn) III
Ammonia (NH_Three) For the V-group
The film was formed by a normal pressure MOCVD method as a raw material. Magnesium
(Mg) doping source is biscyclopentadiene
Rumagnesium (bis- (C_FiveH_Five)_TwoMg)
Was. The source of Si dopant is disilane (Si_TwoH₆)use
Used. The film forming temperature of each of the constituent layers 304 to 307 is 1030
° C. The carrier concentration of the lower cladding layer 304 is
About 3 × 10¹⁸cm^-3The layer thickness was about 2 μm.
The thickness of the light emitting layer 305 is about 100 nm, and the carrier concentration
Is about 1 × 10 ¹⁷cm^-3And n-type Al_0.10Ga_0.90N
The carrier concentration of the upper cladding layer 306 is 3 ×
10¹⁷cm^-3And the layer thickness was about 10 nm. n
Carrier concentration of the GaN contact layer 307 is about 2 × 1
0¹⁸cm^-3And the layer thickness was about 100 nm.

A gold (Au) film having a thickness of about 8 nm was applied to the entire surface of the n-type GaN contact layer 307 by a general vacuum deposition method. Next, rectangular holes 308a and 308b as shown in FIG. 13 were formed in the Au film by using general photolithography means. The rectangular hole 308a has a long side formed by the LED chip 200.
Are provided in parallel with the center line C1, and at a total of two locations that are line-symmetric with the center line C1. The size of the rectangle forming the hole portion 308a was such that the long side was 120 μm and the short side was 50 μm. Another rectangular hole 308b has a long side at the center line C2.
, And at two positions symmetrical with respect to the center line C2. The rectangular hole 308b had a long side of 260 μm and a short side of 50 μm.
Outer edge of projection area 310a of pedestal electrode and rectangular hole 3
The shortest distance between the electrodes 08a and 308b was 20 μm. The distance between the rectangular holes 308a and 308b and the outer edge 200b of the LED was 20 μm.

Next, with the net-shaped conductive electrode 308 having the rectangular holes 308a and 308b remaining on the n-type GaN contact layer 307, indium oxide is formed as the transparent window layer 309 by a general magnetron sputtering method. -A tin (ITO) film was deposited. The specific resistance of the ITO layer is about 4 × 10 ⁻⁴ Ω · cm, and the layer thickness is about 430 nm.
And After applying a general organic photoresist material to the entire surface of the window layer 309, a region where the pedestal electrode 310 is to be provided was patterned by using a known photolithography technique. Thereafter, a titanium (Ti) film was deposited on the entire surface by an electron beam vacuum evaporation method while leaving the patterned resist material. The thickness of the Ti film was about 500 nm. Thereafter, along with the removal of the resist material, the Ti film was left only in the region where the pedestal electrode 310 was to be formed by well-known lift-off means. Thus, a circular pedestal electrode 310 having a diameter of about 120 μm was formed.

In this embodiment, since the chip size (= Q) of the LED 200 is 300 μm, the pedestal electrode 31
The surface area of the open light-emitting region excluding the zero plane area (about 1.1 × 10 ⁻⁴ cm ² ) was about 7.9 × 10 ⁻⁴ cm ² . On the other hand, the total plane area of the rectangular holes 308a and 308b is 3.8 × 10 ⁻⁴ cm ² , and accordingly, the total plane area of the rectangular holes occupying the surface area of the open light-emitting region 307a. The ratio was about 48.1%. The ratio of the portion excluding the conductive electrode 308 on the element plane and the bottom of the pedestal electrode 310 to the entire element plane is about 42%, and the total area of the conductive electrodes 308 on the element plane is smaller than the bottom area of the pedestal electrode. The ratio was about 373%.

After a p-type conductive electrode 311 made of aluminum (Al) is formed on the back surface of a p-type Si single crystal substrate 301, a laminated structure (wafer) is formed by a usual scribing method.
3A was cut and individually subdivided into LED chips 200. Chip (individual element) 200 has a side of 300 μm
And a square. When a current was passed between the p-type conductive electrode 311 and the pedestal electrode 310 in the forward direction, blue light having a wavelength of about 440 nm was emitted through the open light emitting region 307a. Due to the effect of arranging the reticulated conductive electrodes 308, substantially uniform intensity light emission is recognized even in the region of the periphery 200b of the LED 200, and the intensity of light emission measured in a chip state is about 1.1 candela (cd). Met. The forward voltage (Vf: ＠ 20 mA) when a current of 20 mA (mA) was passed was about 3.8 volts (V), reflecting the good ohmic characteristics of the conductive electrode 308.

[0036]

According to the present invention, there is provided a semiconductor LED having a pedestal electrode and a window layer, wherein the mesh electrode has a hole in an open light emitting region of the semiconductor layer forming a high junction barrier with the window layer. Is provided, without unnecessarily reducing the plane area of the open light emitting region, and the LE supplied from the pedestal electrode.
Since the D drive current can flow from the window layer through the conductive electrode, the LED drive current is diffused substantially evenly in the open light emitting region, and the semiconductor light emitting device having a uniform light emission intensity distribution and high light emission intensity
ED can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a planar structure of an LED according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of the LED shown in FIG. 1 along a broken line XY.

FIG. 3 is a schematic plan view of an LED including a conductive electrode according to an eleventh embodiment of the present invention.

FIG. 4 is a schematic plan view of an LED including a conductive electrode according to a twelfth embodiment of the present invention.

FIG. 5 is a schematic plan view of an LED including a conductive electrode according to a thirteenth embodiment of the present invention.

FIG. 6 is a schematic plan view of an LED including a conductive electrode according to a fourteenth embodiment of the present invention.

FIG. 7 is a schematic plan view of another LED including a conductive electrode according to a fourteenth embodiment of the present invention.

FIG. 8 is a schematic plan view of an LED including a conductive electrode according to a fifteenth embodiment of the present invention.

FIG. 9 is a schematic plan view of another LED including a conductive electrode according to a fifteenth embodiment of the present invention.

FIG. 10 is a schematic plan view of still another LED provided with a conductive electrode according to a fifteenth embodiment of the present invention.

FIG. 11 is a schematic plan view of the LED according to the first embodiment of the present invention.

FIG. 12 is a schematic cross-sectional view of the LED of FIG. 11 taken along a broken line AA ′.

FIG. 13 is a schematic plan view of an LED according to a second embodiment of the present invention.

FIG. 14 is a schematic cross-sectional view of the LED of FIG. 13 along the broken line BB ′.

[Explanation of symbols]

Reference Signs List 1A laminated structure 2A laminated structure 10 III-V compound semiconductor LED 10a pn junction type double hetero junction light emitting section 10b Outer edge of LED chip 20 III-V compound semiconductor LED 30 III-V compound semiconductor LED 40 III-V Group III compound semiconductor LED 50 III-V group compound semiconductor LED 60 III-V group compound semiconductor LED 70 III-V group compound semiconductor LED 80 III-V group compound semiconductor LED 90 III-V group compound semiconductor LED 100 AlGaInP-based LED 100b LED Outer edge 101 Single crystal substrate 102 Buffer layer 103 Bragg reflection layer 104 Lower cladding layer 105 Light emitting layer 106 Upper cladding layer 106a Open light emitting area 107 Conductive electrode 108 Window layer 109 Pedestal electrode 109a Projection area of pedestal electrode 1 Reference Signs List 10 conductive electrode 111 circular hole 112 elliptical hole 113 rectangular hole 114 hexagonal hole 115 band-shaped hole d spacing between adjacent conductive electrodes d1 center of LED chip Line C2 Center line of LED chip L1 Diagonal line of LED chip L2 Diagonal line of LED chip M Center point of LED chip (pedestal electrode) Q Size of LED chip R Center point M of planar shape of pedestal electrode at center of shape of conductive electrode Distance 200 GaInN-based LED 200b Outer edge of LED 201 p-type GaAs single crystal substrate 202 p-type GaAs buffer layer 203 Bragg reflection layer 204 AlGaInP-based lower clad layer 205 AlGaInP-based light-emitting layer 206 AlGaInP-based upper clad layer 206a open light-emitting region 207 conductive Electrode 207a First arc-shaped hole 2 7b Second arc-shaped rear portion 207c Circular hole portion 208 Conductive transparent oxide window layer 209 Pedestal electrode 209a Projection region of pedestal electrode 210 P-type conductive electrode 301 p-type Si single crystal substrate 302 p-type BP low-temperature buffer Layer 303 p-type BP high-temperature buffer layer 304 p-type GaN lower cladding layer 305 GaInN light-emitting layer 306 n-type AlGaN upper cladding layer 307 n-type GaN contact layer 307 a open light-emitting area 308 mesh conductive electrode 308 a rectangular hole 308 b rectangular Hole 309 Conductive transparent oxide window layer 310 Pedestal electrode 310a Projected area of pedestal electrode 311 Conductive electrode on back side of substrate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koji Hoshina 1505 Shimokagemori, Chichibu City, Saitama Prefecture Showa Denko Co., Ltd. F-term 5F041 AA03 AA04 CA03 CA34 CA35 CA40 CA85 CA88 CA92 CA93 CA98

Claims (15)

[Claims] 1. A semiconductor light-emitting diode having a light-emitting layer, a window layer, and a pedestal electrode for connection, comprising a mesh-shaped conductive electrode in an element plane other than a projection area of the pedestal electrode. 2. The planar shape of the element is such that the length of one side is 150 to 150.
2. The semiconductor light emitting diode according to claim 1, wherein the semiconductor light emitting diode has a substantially square shape of 500 μm. 3. The semiconductor light emitting diode according to claim 1, wherein the mesh-shaped conductive electrodes are laid on substantially the entire surface of the element plane other than the projection region of the pedestal electrode. 4. The device according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane is point-symmetric with respect to the center point of the projection area of the pedestal electrode. Semiconductor light emitting diode. 5. The device according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane is line-symmetric with respect to a line passing through the center point of the projection area of the pedestal electrode. 13. A semiconductor light emitting diode according to item 9. 6. The light-emitting layer according to claim 1, wherein the light-emitting layer is formed of a group III-V compound semiconductor.
13. A semiconductor light emitting diode according to item 9. 7. The semiconductor light emitting diode according to claim 1, wherein the window layer includes a layer formed from an oxide. 8. The semiconductor diode according to claim 1, wherein the mesh-shaped conductive electrode includes a layer formed of a metal. 9. The method according to claim 1, wherein the total area of the mesh-shaped conductive electrodes on the element plane is in the range of 10 to 500% of the bottom area of the pedestal electrode. 1
A light-emitting diode according to the item. 10. The device according to claim 1, wherein the area of the portion excluding the mesh-shaped conductive electrode and the bottom of the pedestal electrode on the element plane is in the range of 30 to 95% in terms of the area ratio to the entire element plane. The light emitting diode according to claim 1. 11. The method according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane includes a circular hole in a range of 5 to 200 μm in diameter.
13. A semiconductor light emitting diode according to item 9. 12. The device according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane includes a region having a major axis in a range of 5 to 200 μm and formed in an elliptical shape. A semiconductor light-emitting diode according to claim 1. 13. The device according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane includes a rectangular hole formed in a range of 5 to 200 μm on one side. The semiconductor light emitting diode according to claim 1. 14. The device according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane includes a polygonal hole having a side length of 5 to 200 μm.
The semiconductor light-emitting diode according to any one of the preceding claims. 15. The device according to claim 1, wherein the shape of the mesh-shaped conductive electrode in the element plane includes a band-shaped hole having a width of 5 to 100 μm.
13. A semiconductor light emitting diode according to item 9.