JPH0888404A - Plane light emitting type semiconductor light emitting device - Google Patents

Abstract

PURPOSE: To provide a light emitting diode which makes possible improvement of luminous efficacy in a light emitting portion made of InGaAlP and improvement of luminance. CONSTITUTION: A light emitting diode has an n-GaAs substrate 11, an n-InGaAlP clad layer 12 formed on the substrate 11, a multilayer light emitting layer 13 formed on the clad layer 12, and a p-InGaAlP clad layer 15 formed on the multilayer light emitting layer 13, for leading out a light from the plane opposite to the substrate 11. In this light emitting diode, the multilayer light emitting layer 13 is caused to have a multiple quantum well structure in which a strain quantum well layer 13a having a tensile strain and a strain relaxation barrier layer 13b having a compression strain are stacked.

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 using a compound semiconductor material, and more particularly to a surface emitting semiconductor light emitting device using a strained quantum well structure in which lattice strain is introduced into an active layer region.

[0002]

2. Description of the Related Art InGaAlP materials exclude nitrides
It has the largest direct transition type band gap in the III-V compound semiconductor mixed crystal, and is attracting attention as a light emitting device material in the 0.5 to 0.6 μm band. In particular, p is used as a substrate of GaAs and has a light emitting portion made of InGaAlP that is lattice-matched to this
The n-junction type light emitting diode (LED) is different from the conventional one using an indirect transition type material such as GaP or GaAsP.
High-intensity light emission from red to green is possible. However, even with this type of LED, the luminous efficiency in the shorter wavelength region (green emission) was not always sufficient.

FIG. 9 shows a cross section of the structure of a conventional LED having an InGaAlP light emitting portion. In the figure, 1 is n-GaA
s substrate, 2 is n-InGaAlP clad layer, 3 is In
GaAlP active layer, 4 p-InGaAlP cladding layer, 5 p-GaAlAs current spreading layer, 6 p-GaA
s contact layer, 7 is a p-side electrode made of AuZn, and 8 is an n-side electrode made of AuGe.

The mixed crystal composition is set so that the energy gap of the InGaAlP active layer 3 is smaller than that of the clad layers 2 and 4, so that the active layer 3 can receive light and carriers.
It has a double hetero structure that is confined in. Also, p
-The composition of the GaAlAs current diffusion layer 5 is InGaAlP.
It is set to be substantially transparent to the wavelength of light emitted from the active layer 3.

In the structure of FIG. 9, the active layer 3 has a thickness of 0.
2 μm undoped In _0.5 (Ga _1-x Al _x ) _0.5
When P (x = 0.4), the conductivity type was n type, and the concentration was about 1 to 5 × 10 ¹⁶ cm ⁻³ . At this time, the emission wavelength is 565 nm (green) and the emission efficiency is DC20.
It was 0.07% in mA. When x = 0.3, the emission wavelength is 585 nm (yellow) and the emission efficiency is DC20.
It was as narrow as 0.4% in mA, and the characteristic merit over GaP and GaAsP systems was not necessarily found. On the other hand, x
= 0.2, the emission wavelength is 620 nm (orange), the emission efficiency is 1.5% at DC 20 mA, and the emission wavelength exceeds that of the GaAlAs system without particularly removing the GaAs substrate 1 serving as an absorber. Efficiency was obtained.

As described above, it is known from the experiments by the present inventors that the luminous efficiency changes depending on the Al composition x of the active layer (Appl. Phys. Lett. 58 (1991) 1010). .
It is considered that this is because the influence of the non-radiative centers is increased by increasing the Al mixed crystal ratio in the crystal of the active layer (J. Electron Mater 20 (1991) 687). Against this background, trial production has been performed, such as changing the ordered arrangement of atoms, which is a characteristic of this InGaAlP material, under crystal growth conditions to shorten the emission wavelength without changing the Al composition.

In addition to this, as a means for improving the luminous efficiency in the short wavelength region, a quantum well (QW: Quantum Well) is formed in the active layer.
The method of adopting the structure is considered to be effective. The QW structure is formed by sandwiching a quantum well layer having a thickness equal to or less than the wavelength of the electron wave function with a barrier layer having a larger energy gap and serving as a barrier to electrons in the quantum well.
QW: Single Quantum Well) or 2 or more (MQW: Mul
tiple Quantum Well). In a semiconductor light emitting device having a quantum well structure as an active layer, the energy gap due to quantization of electronic states is equivalently increased, and the emission wavelength is shortened.

Such shortening of wavelength is an essential phenomenon in the quantum well structure, and is also found in other material systems such as GaAlAs system. However, when applied to a light emitting device using an InGaAlP system, it has the following problems. That is, in the InGaAlP material, the change in the band discontinuity value on the conduction band side due to the change in Al composition is small, so that when the quantum well structure is formed, the conduction band side becomes a very shallow well. Therefore, carriers (electrons) injected into the well layer
Leaks to the barrier layer.

The Al composition of the barrier layer is relatively high, and there is a non-radiative center generated by increasing chemically active Al, and leaked electrons are non-radiatively recombined through this. If the band gap of the barrier layer is increased, the well can be deepened, but as a result, the Al composition is increased, which causes a problem of increasing non-radiative centers in the barrier layer and a decrease in carrier injection efficiency.

Further, as a method of shortening the emission wavelength without changing the Al composition, lattice strain has been introduced into the crystal of the active layer. However, increasing the amount of strain leads to an increase in lattice defects in the crystal, and further, to obtain a film thickness in which carriers (electrons) injected into the active layer are sufficiently confined in the active layer in relation to the critical film thickness. Will cause problems such as difficulty. Therefore, it cannot be said that it is necessarily effective in improving the luminous efficiency.

From the above, in the light emitting device using the InGaAlP material, it is necessary to optimize the structural parameters of the light emitting portion in order to improve the efficiency of light emission of short wavelength in particular.

[0012]

As described above, the conventional I
Although a quantum well structure and a strain introduction technique are adopted in order to achieve high efficiency in a short wavelength in a semiconductor light emitting device having an active layer made of nGaAlP, it is impossible to effectively confine carriers in the well layer. There was a problem that characteristics were likely to deteriorate due to dislocations, defects, and non-radiative centers.

The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the luminous efficiency of a light emitting portion made of InGaAlP or the like and to improve the brightness. It is to provide a light emitting device.

[0014]

The essence of the present invention is InG
In order to improve the light emission efficiency of the light emitting portion made of a material such as aAlP, tensile strain is applied to the light emitting layer, and the film thickness is not limited by the strain amount at this time.

That is, the present invention provides a compound semiconductor substrate of the first conductivity type, a clad layer of the first conductivity type formed on the substrate, and a multilayer film light emitting layer formed on the clad layer.
A surface-emitting type semiconductor light-emitting device that includes a second-conductivity-type cladding layer formed on the multilayer light-emitting layer and takes out light from a plane parallel to the substrate. The layer is composed of semiconductor layers having positive and negative lattice mismatch.

Here, the following are preferred embodiments of the present invention. (1) The multilayer light emitting layer and the cladding layer should be made of InGaAlP-based material. (2) The multilayer light emitting layer is composed of a multiple quantum well structure in which a strained quantum well layer having tensile strain (or compressive strain) and a strain relaxation barrier layer having compressive strain (or tensile strain) are laminated. (3) Let Δa1,2 and d1,2 be the lattice mismatch rate between the strained layer and the strain relaxation layer and the substrate, respectively, and let Δa1 × d1 =-(Δ
The relationship of a2 × d2) is established. (4) As the strained layer, In _1-x (Ga _1-y Al _y ) _x P (x
> 0.51) and In _1-s (Ga) as a strain relaxation layer.
_1-m Al _m ) _s P (s <0.51) is used. (5) In the relationship of (4), y <m. (6) The total thickness of the strained quantum well layer should be 150 nm or more, and the lattice constant should be -0.5% or more of that of the substrate.

[0017]

According to the present invention, by using the strain relaxation layer in which the inverse strain is applied to the strained layer, the thickness of the strained layer, which has been limited by the critical thickness until now, can be increased. Carriers can be sufficiently confined, and Al
The effect of strain that can shorten the wavelength without increasing the composition can be more effectively exerted. Further, by making the Al composition of the strain relaxation layer larger than that of the strain layer, it is possible to form a multiple quantum well structure having a large energy gap difference on the conduction band side (deep well). Therefore, due to the phenomenon that the band gap difference with the cladding layer or the barrier layer becomes smaller due to the equivalent increase in energy gap caused by the quantum well structure without strain, the overflow of injected carriers (the injected carriers leak from the active region). Flow rate) can be suppressed. Further, by increasing the amount of strain, the heavy holes and the light holes, which have been degenerated on the valence band side and have a large effective mass, are separated from each other, whereby the luminous efficiency of spontaneous emission light can be improved.

The strain referred to here is the lattice constant a0 of the crystal used for the substrate and the InGaAlP crystal grown on it.
It can be expressed as follows by the lattice constant a of the material. That is, {(a-a0) / a0} * 100%, and the tensile strain has a negative value.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1A is a sectional view showing a schematic structure of a light emitting diode (LED) according to a first embodiment of the present invention. In the figure, 11 is an n-GaAs substrate, and n-In _0.5 (Ga _{1 -A} Al _A ) _{0.5 is formed} on one main surface of the substrate 11.
P cladding layer 12, strain relaxation quantum well active layer 13, and p
-In _0.5 emitting portion composed of _{(Ga 1-B Al B)} 0.5 P cladding layer 14 is grown. Further, on the light emitting portion, the p-Ga _1-c Al _c As current diffusion layer 15 and the p-G are formed.
The aAs contact layer 16 is grown and formed, and the contact layer 16 is processed into a circular shape, for example, by selective etching.

Then, Au--Zn is formed on the contact layer 16.
Is formed, and the n-side electrode 18 made of Au—Ge is formed on the other main surface of the substrate 11. The growth of each layer is performed by the metal organic chemical vapor deposition (MOCV) method.
Method D) was used.

The strain relaxation quantum well active layer 13 is shown in FIG.
As shown in, strained quantum well layer (strained layer) 1 having tensile strain 1
3a and a strain relaxation barrier layer (strain relaxation layer) 13b having a compressive strain are laminated. The material of the strained quantum well layer 13a is In _1-x (Ga _1-y Al _y ) _x P (x> 0.5,0).
≦ y ≦ 1), the material of the strain relaxation layer 13b is In _1-s (Ga)
_1-m Al _m ) _s P (s <0.5, 0 ≦ m ≦ 1).

An example in which the strain relaxation quantum well active layer portion thus set is applied to the surface emitting LED shown in FIG. 1A will be described below. The strained quantum well layer 13a has a thickness of 15
nm, strain-1% In _0.41 (Ga _0.7 Al _0.3 ) _0.59
P, strain relaxation barrier layer 13b has a thickness of 20 nm, strain amount +0.3
75% of In _0.54 ( _{Ga 0.3} Al _0.7 ) _0.46 P as 2
No. 0, the cladding layer 12 was n-In _0.5 Al _0.5 P, and the cladding layer 14 was p-In _0.5 Al _0.5 P. The current diffusion layer 15 was made of p-Ga _0.3 Al _0.7 As with a thickness of 7 μm. Impurity doping of the clad layers 12 and 14 and the current diffusion layer 15 is performed by using Zn as an impurity for the p-type
4 is 3 × 10 ¹⁷ cm ⁻³ , and the current spreading layer 15 is 3 × 10 ¹⁸ c
m ⁻³ , n-type has Si as an impurity, and the cladding layer 12 has 3 ×
It was set to about 10 ¹⁷ cm ^-3 .

The total thickness of the strained quantum well layer 13a is 300 nm.
From the relationship between the amount of strain and the critical film thickness shown in FIG.
This means that the critical film thickness of 0.5% is thicker than 20 nm. However, the crystal growth of the device structure shown in FIG.
By observing the surface morphology of the crystal, defects of lattice relaxation observed when the critical thickness was exceeded were not found. In addition, in the evaluation by X-ray diffraction, it was confirmed that the crystal growth layer was lattice-matched with the substrate crystal. It is considered that this is because the introduction of the strain relaxation layer has enabled thick film growth. In addition, similar characteristics were confirmed for 40 pairs.

The current-light output characteristics of this LED are shown in FIG. In the figure, A is the current-light output characteristic in the case of having the strain relaxation quantum well structure active layer of the present embodiment, and B is the Al mixed crystal ratio of the InGaAlP active layer 3 in the conventional structure shown in FIG. It is a current-light output characteristic in the case. The emission wavelengths of the two elements shown in FIG.
It was about m. Comparing the optical outputs of the strain-relaxed quantum well structure and the conventional structure (bulk active layer) under an operating current of 20 mA, the strain-relaxed quantum well structure was able to obtain approximately three times the optical output.

FIG. 4 shows the relationship between the emission wavelength and the external quantum efficiency at an operating current of 20 mA. The white circles in the figure are the results of the element having the strain relaxation quantum well structure active layer of the present embodiment, and the black circles are InGa in the conventional structure shown in FIG.
The Al mixed crystal ratio of the AlP active layer 3 is 0.2, 0.3, 0.4.
Is the result of the element. The external quantum efficiency of the structure of this example was higher than that of the conventional structure at the same wavelength, and the value was 0.7%.

As described above, according to the present embodiment, as the quantum well active layer 13 constituting the light emitting layer, the strain relaxation barrier layer 13b having compressive strain of reverse strain is used for the strained quantum well layer 13a having tensile strain. As a result, the film thickness of the quantum well active layer 13 that was limited by the critical film thickness can be made sufficiently thicker than this critical film thickness. Therefore, the introduction of strain can shorten the wavelength without increasing the Al composition, and can also sufficiently confine carriers. Therefore, I
It is possible to improve the luminous efficiency of the light emitting portion made of nGaAlP, and it is possible to significantly improve the luminance. (Embodiment 2) FIG. 5A is a sectional view showing a schematic configuration of a second embodiment of the present invention. The difference between this embodiment and the above-described embodiment is that the material forming the device is made of II-VI group Z
That is, the nSe system is used.

In the figure, 51 is a p-GaAs substrate, and p-InAlP / InGaAlP is formed on one main surface of the substrate 51.
/ InGaP-based easy-to-carry layer 52, p-ZnSe
A buffer layer 53 is grown, and p is formed on the buffer layer 53.
A light emitting portion including a -ZnMgSeS cladding layer 54, a strain relaxation quantum well active layer 55, and an n-ZnMgSeS cladding layer 56 is grown. Furthermore, n-
A ZnSe contact layer 57 is formed.

Ni is formed on a part of the contact layer 57.
An n-side electrode 58 made of -Au is formed, and a p-side electrode 59 made of Ti-Au is formed on the other main surface of the substrate 51. It should be noted that N and Cl were used as both the p and n impurity materials, and the molecular beam epitaxial growth method (MBE method) was used for crystal growth.

The strain relaxation quantum well active layer 55 is shown in FIG.
Strained quantum well layer (strained layer) 55a having compressive strain as shown in FIG.
And a strain relaxation barrier layer (strain relaxation layer) 55b having tensile strain. The material of the strained quantum well layer 55a is Cd _x Zn _1-x Se (x> 0) or ZnSe _x Te.
_1-x (x <1) and the material of the strain relaxation barrier layer 55b is ZnS
_x Se _1-x (x> 0).

An example in which the strain relaxation quantum well active layer portion thus set is applied to the surface emitting LED shown in FIG. 5A will be described below. The strain quantum well layer material used here is CdZnSe, and the strain amount and the film thickness are + 2% and 5 nm. Further, the strain amount and the film thickness of the strain relaxation barrier layer ZnSSe are −1.
%, 10 nm. The logarithm was set to 40. In addition,
The strain referred to here is {(a-a0) / a0 by using the lattice constant a0 of ZnSe crystal and the lattice constant a of other crystal growth layers.
} × 100%, and the tensile strain has a negative value. Further, in this example as well, similar to the above-mentioned examples, no defects considered to be due to lattice relaxation were observed.

An operating current of 20 mA is applied to the element having such a structure.
When a bias of 1 was applied, a high-luminance light emission with an altitude of 10 cd was obtained with a blue-green light emission wavelength of 530 nm. (Embodiment 3) FIG. 6A is a sectional view showing a schematic configuration of a third embodiment of the present invention. This embodiment is different from the above-described embodiments in that the material forming the device is InGaA.
That is, the 1N system is used.

In the figure, reference numeral 61 is a sapphire substrate, on which a GaAlN-based buffer layer 62 is grown, and n-GaN layers 63, n- are formed on the buffer layer 62.
GaAlN cladding layer 64, strain relaxation quantum well active layer 65
And a light emitting portion composed of the p-GaAlN cladding layer 66 is grown. Furthermore, a p-GaN contact layer 67 is grown on this light emitting portion. Then, a p-side electrode 68 made of Ni-Au is formed on a part of the contact layer 67, and an n-side electrode 69 is formed on the other main surface of the n-GaN 63 using Ti-Au or Ti-Al. ing.
The p and n impurity materials are Mg and S, respectively.
i is used for crystal growth by metalorganic vapor phase epitaxy (MOCVD
Method) was used.

The strain relaxation quantum well active layer 65 is shown in FIG.
As shown in, the quantum well layer 65a having a compressive strain and the strain relaxation barrier layer (strain relaxation layer) 65b having a tensile strain are laminated. The material of the quantum well layer 65a is undoped In _x Ga _1-x N (x> 0), and the strain relaxation barrier layer 65 is formed.
The material of b is Ga _1-x (InAl) _x N (x <1).

An example in which the strain relaxation quantum well active layer portion thus set is applied to the surface emitting LED shown in FIG. 6A will be described below. Strained quantum well layer InG used here
The strain amount and film thickness of aN are + 2% and 5 nm, and the strain relaxation barrier layer is made of GaAlN and the strain amount and film thickness are -1% and 10%.
nm and the logarithm thereof was 40. The strain referred to here is the lattice constant a0 of the GaN crystal and the lattice constant a of other crystal layers.
Is used to express the relationship of {(a-a0) / a0} * 100%, and the tensile strain has a negative value. Also, in this example, as in the case of the above-mentioned examples, no defects considered to be due to lattice relaxation were found.

An operating current of 20 mA is applied to the element having such a structure.
When a bias of 2 was applied, high-luminance light emission with a blue light having an emission wavelength of 450 nm and a luminous intensity of 5 cd was obtained. The full width at half maximum of this emission spectrum was as narrow as -10 mm, and light emission excellent in monochromaticity was obtained. Further, when a light emitting center was formed by doping Zn into the strained quantum well layer 65a and operated with a bias of 20 mA, a high-luminance light emission having a light emission peak wavelength of 500 nm and a luminous intensity of 7 cd was obtained. (Embodiment 4) FIG. 7A is a sectional view showing a schematic configuration of a fourth embodiment of the present invention. The difference of this embodiment from the above-described embodiments is that the device is a surface emitting laser.

In the figure, reference numeral 71 denotes an n-GaAs substrate, and an n-GaAs buffer layer 72 is provided on the substrate 71 for n.
Bragg reflection layer 73 is formed composed of 30 pairs of -AlAs and n-Ga _0.5 Al _0.5 As. Furthermore, n-In _0.5 (G
a _0.3 Al _0.7 ) _0.5 P cladding layer 74, strain relaxation quantum well active layer 75, p-In _0.5 (Ga _0.3 Al _0.7 ).
_A light emitting portion made of a _0.5 P cladding layer 76 is formed. Furthermore, p-Ga is formed on the clad layer 76.
An AlAs layer 77 is formed as a first contact layer,
A Bragg reflection layer 78 composed of 30 pairs of p-AlAs and p-Ga _0.5 Al _0.5 As is formed, and a ridge is formed by these two.

On the side surface of this ridge, p-GaA is formed.
An s contact layer 79 is formed as a second contact layer, and Au-- on the upper surface of the contact layer 79.
A p-side electrode 81 made of Zn is formed, and an n-side electrode 82 made of Au—Ge is formed on the main surface of the substrate 71.
The contact layer 77 had a thickness of 1 μm and the ridge had a diameter of 20 μm. The crystal growth was performed by the metal organic chemical vapor deposition method (MOCVD method).

The current injection 82 in this embodiment is performed by the electrode 8
1-p-GaAs contact layer 79-Bragg reflection layer 7
8 and the side surface of the p-GaAlAs contact layer 77. Therefore, the carrier concentration of the p-GaAlAs contact layer 77 is set high, and the Al mixed crystal ratio is set to 0.5 so as not to cause a loss with respect to the emission wavelength. The current confinement in this embodiment is caused by the InGaAlP between the clad layer 76 and the contact layer 79.
This is performed by the hetero barrier 83 between the / GaAs heterojunctions.

The strain relaxation quantum well active layer 75 is shown in FIG.
Strained quantum well layer (strained layer) 75 having tensile strain as shown in
6 of a and 7 layers of a strain relaxation barrier layer (strain relaxation layer) 75b having a compressive strain sandwiching the well layer 75a are laminated. The material of the strained quantum well layer 75a is In _1-x (Ga
_{1-y Al y) x P} (x < in 0.5,0 ≦ y ≦ 1), the material of the strain relaxation barrier layer _{75b In 1-s (Ga 1} -m Al m) s
P (s> 0.5, 0 ≦ m ≦ 1).

FIG. 8 shows the operating current-optical output characteristics of the surface emitting laser having the strain relaxation quantum well active layer thus set. The strained quantum well layer 75a of the device shown here has a thickness of 5n.
m, strain + 2% of In _0.75 Ga _0.25 P, the strain relaxation barrier layer 75 b has a thickness of 10 nm, strain -1% of In _0.35 (G
a _0.6 Al _0.4 ) _0.65 P. The strain referred to here has a relationship of {(a−a0) / a0} × 100 using the lattice constant a0 of GaAs used for the substrate and the lattice constant a of the InGaAlP crystal grown on it. That is, the tensile strain has a negative value. The oscillation wavelength of this device is 6
At 75 nm, the laser oscillation threshold is 2 m as shown in FIG.
A, the maximum light output was 8 mW.

Generally, when the amount of strain is increased to approach the critical film thickness, defects such as misfit dislocations occur and laser oscillation becomes difficult and the kink level sharply decreases. The element did not show such characteristics, and excellent laser characteristics with a low threshold value were obtained. Also, it is not desirable to increase the thickness of the light emitting portion in a normal laser, but in the surface emitting laser, there is no problem in increasing the thickness of the light emitting portion, and the gain can be increased by increasing the thickness. Is larger and the threshold is lower. Therefore, the effect of the present invention that the film thickness can be increased by giving positive and negative strains to the quantum well layer and the barrier layer is great.

The present invention is not limited to the above embodiments. In the embodiment, the strain relaxation layer is used to set the total amount of strain in the light emitting portion to approximately 0. However, the same effect can be obtained by leaving the strain in a range where lattice relaxation does not occur. Further, the lattice mismatch material of the strain relaxation quantum well structure is not limited to the above-mentioned materials, and InGaA
Similar effects can be obtained by using an sP-based or I-III-VI group chalcopyrite material. In addition, various modifications can be made without departing from the scope of the present invention.

[0043]

As described above in detail, according to the present invention, in a semiconductor light emitting device having a light emitting portion made of InGaAlP or the like formed on a compound semiconductor substrate, the light emitting portion is provided with a multi-layer having different lattice strains of positive and negative. And the total strain amount is almost 0
By making it so that it becomes possible to grow a thick film capable of effectively confining injected carriers, and also by forming a multiple quantum well structure in the multiple layers, an Al mixed crystal ratio with an increase in non-radiative centers is obtained. It is possible to realize a semiconductor light emitting device capable of achieving high light emission efficiency at a short wavelength without increasing the number.

[Brief description of drawings]

FIG. 1 is a diagram showing a device structure, a band structure and a strain amount of a light emitting diode according to a first embodiment.

FIG. 2 is a diagram showing a relationship between a lattice mismatch rate (strain amount) and a critical film thickness.

FIG. 3 is a diagram showing current-light output characteristics of an example device and a conventional device.

FIG. 4 is a diagram showing the relationship between the emission wavelength and external quantum efficiency in the device of the example and the conventional device.

FIG. 5 is a diagram showing an element structure, a band structure and a strain amount of a light emitting diode according to a second embodiment.

FIG. 6 is a diagram showing an element structure, a band structure and a strain amount of a light emitting diode according to a third embodiment.

FIG. 7 is a diagram showing an element structure, a band structure and a strain amount of a surface emitting laser according to a fourth embodiment.

FIG. 8 is a diagram showing operating current-optical output characteristics of a surface emitting laser according to a fourth embodiment.

FIG. 9 is a cross-sectional view showing a device structure of a conventional LED having an InGaAlP light emitting portion.

[Explanation of symbols]

11 ... n-GaAs substrate 12 ... n-InGaAlP clad layer 13, 55, 65, 75 ... strain relaxation quantum well active layer 13a, 55a, 65a, 75a ... strain quantum well layer 13b, 55b, 65b, 75b ... strain relaxation barrier Layer 14 ... p-InGaAlP clad layer 15 ... p-GaAlAs current diffusion layer 16 ... p-GaAs contact layer 17, 59, 68, 81 ... p-side electrode 18, 58, 69, 82 ... n-side electrode 51 ... p-GaAs Substrate 52 ... Easy-to-carry layer made of p-InAlP / InGaAlP / InGaP system 53 ... p-ZnSe buffer layer 54 ... p-ZnMgSeS cladding layer 56 ... n-ZnMgSes cladding layer 57 ... n-ZnSe contact layer 61 ... Sapphire substrate 62 ... GaAlN-based buffer layer 63 ... n-GaN layer 64 ... n-GaA 1N clad layer 66 ... p-GaAlN clad layer 67 ... p-GaN contact layer 71 ... n-GaAs substrate 72 ... n-GaAs buffer layer 73, 78 ... Bragg reflection layer 74 ... n-InGaAlP clad layer 76 ... p-InGaAlP clad layer Layer 77 ... p-GaAlAs first contact layer 79 ... p-GaAs second contact layer

[Procedure amendment]

[Submission date] November 9, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

An example in which the strain relaxation quantum well active layer portion thus set is applied to the surface emitting LED shown in FIG. 1A will be described below. The strained quantum well layer 13a has a thickness of 15
nm, strain- 0.5 % of In _0.41 (Ga _0.7 Al _0.3 ).
_0.59 P, thickness of strain relaxation barrier layer 13b is 20 nm, strain amount +
20 pairs of 0.375% In _0.54 ( _{Ga 0.3} Al _0.7 ) _0.46 P and the cladding layer 12 made of n-In _0.5 Al _0.5.
P, and the cladding layer 14 was p-In _0.5 Al _0.5 P.
The current diffusion layer 15 is 7 μm thick p-Ga _0.3 Al _0.7 A
s. Impurity doping of the clad layers 12 and 14 and the current diffusion layer 15 was performed by using Zn as an impurity for the p-type, the cladding layer 14 was 3 × 10 ¹⁷ cm ⁻³ , and the current diffusion layer 15 was 3 × 1.
0 ¹⁸ cm ⁻³ , n-type has Si as an impurity, and the cladding layer 12
Was about 3 × 10 ¹⁷ cm ⁻³ .

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG.

Claims (2)

[Claims] 1. A first-conductivity-type compound semiconductor substrate, a first-conductivity-type clad layer formed on the substrate, a multilayer light-emitting layer formed on the clad layer, and the multi-layer light-emitting layer. A clad layer of the second conductivity type formed above,
A semiconductor light emitting device for extracting light from a plane parallel to a substrate, characterized in that the multilayer light emitting layer is constituted by a semiconductor layer having a positive and negative lattice mismatch with respect to the substrate. Light emitting type semiconductor light emitting device. 2. The multi-layered light emitting layer has a multiple quantum well structure in which a strained quantum well layer having tensile strain or compressive strain and a strain relaxation barrier layer having compressive strain or tensile strain are laminated. The surface emitting semiconductor light emitting device according to claim 1.