JP2002261321A - Semiconductor light emitting device - Google Patents

Abstract

[PROBLEMS] To provide a semiconductor light emitting device with high productivity and high luminous efficiency, which can effectively prevent diffusion of impurities between a p-type cladding layer and an active layer and obtain desired light emitting characteristics. . An upper surface of a substrate 1 made of single crystal silicon is provided.
1. A semiconductor light emitting device comprising a light emitting element 2 made of a GaAs-based compound semiconductor and having an n-type cladding layer 4, an active layer 5 and a p-type cladding layer 7 sequentially laminated, wherein GaAs between the mold cladding layer 7 and the active layer 5
s-based compound semiconductor as main component and carbon atom (C)
At a concentration of 5 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ cm ⁻³ .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an LED (Light Emi)
The present invention relates to a semiconductor light emitting device mounted as a light emitting device such as an array head.

[0002]

2. Description of the Related Art Conventionally, semiconductor light emitting devices have been used as light emitting devices such as LED array heads.

As such a conventional semiconductor light emitting device, for example, as shown in FIG.
Having a structure in which a buffer layer 23, an n-type cladding layer 24, an active layer 25, a p-type cladding layer 26, and a p-type contact layer 29 are sequentially epitaxially grown on the upper surface of the light emitting element 22. When a predetermined voltage is applied between the n-type cladding layer 24 and the p-type cladding layer 26 of the light emitting element 22 via the electrodes 27 and 28 which are ohmically connected to the buffer layer 23 and the p-type contact layer 29, respectively. The electrons in the n-type cladding layer 24 and the holes in the p-type cladding layer 26 are injected into the active layer 25, and the injected electrons and holes are recombined in the active layer 25. The device functions as a semiconductor light emitting device by converting generated energy into light and emitting the light to the outside.

The n-type cladding layer 24, the active layer 25, the p-type cladding layer 26 and the like constituting the light emitting element 22 are doped with impurities for controlling conductivity. The impurities such as Si and Ge are contained in the p-type cladding layer 24, and the impurities are contained in the active layer 25 and the p-type cladding layer 26.
Impurities such as n, Mg, Cd, and Be are doped at predetermined concentrations.

[0005]

However, according to the above-mentioned conventional semiconductor light emitting device, the p-type cladding layer 26 is formed.
Since impurities such as Zn, Mg, Cd, and Be used for doping the semiconductor have a relatively large diffusion coefficient, the light emitting element 22 may be, for example, 30 when manufacturing a semiconductor light emitting device.
When exposed to a high temperature of 0 ° C. to 400 ° C., diffusion of impurities contained in each layer may be promoted and may enter an adjacent layer. In this case, it is necessary to accurately control the impurity concentration of each layer. This has the disadvantage that it becomes impossible to obtain the desired light emission characteristics.

Therefore, in order to solve the above-mentioned disadvantage, Zn
It has been proposed that a diffusion suppressing layer containing almost no impurities such as Al and Mg is interposed between the p-type cladding layer and the active layer, and the diffusion suppressing layer prevents diffusion of impurities between the p-type cladding layer and the active layer.

However, in order to effectively suppress the diffusion of impurities using the above-described diffusion suppressing layer, it is necessary to increase the thickness of the diffusion suppressing layer to about 2 μm to 4 μm. In addition to requiring a long time for epitaxial growth of the layer, a high voltage must be applied between the n-type cladding layer and the p-type cladding layer in order to obtain a desired emission luminance during use. The drawback of lowering is induced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned drawbacks, and has as its object to provide a high production method capable of effectively preventing diffusion of impurities between a p-type cladding layer and an active layer to obtain a desired light emitting characteristic. It is an object of the present invention to provide a semiconductor light emitting device with high luminous efficiency.

[0009]

A semiconductor light emitting device according to the present invention comprises an n-type cladding layer, an active layer, and a p-type cladding layer formed of a GaAs compound semiconductor on an upper surface of a single crystal silicon substrate. A semiconductor light emitting device having a light emitting element formed by lamination, wherein a GaAs compound semiconductor is a main component between a p-type cladding layer and an active layer of the light emitting element, and carbon atoms (C) are 5 × 10 5 ¹⁸ cm ^-3 to 1 x 1
The present invention is characterized in that a diffusion suppressing layer containing a concentration of 0 ²⁰ cm ^-3 is interposed.

[0010] In the semiconductor light emitting device of the present invention, the compound semiconductor forming the diffusion suppressing layer is Al _x Ga _{1 -x} As.
(0 <x ≦ 0.3).

Further, in the semiconductor light emitting device according to the present invention, the thickness of the diffusion suppressing layer is 0.01 μm to 0.2 μm.

Further, in the semiconductor light emitting device according to the present invention, the impurity doped in the active layer and the p-type cladding layer is any one of Zn, Mg, Cd, and Be.

According to the semiconductor light emitting device of the present invention, GaAs
Between a p-type cladding layer and an active layer of a light emitting device formed of an s-based compound semiconductor, a GaAs-based compound semiconductor is used as a main component, and C is set to 5 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ cm.
^Since the diffusion suppression layer containing ^-3 concentration was interposed,
Since C in the diffusion suppressing layer serves as a barrier, diffusion of other impurities doped into the p-type cladding layer and the active layer can be effectively prevented, and the light emitting element can be used when manufacturing a semiconductor light emitting device. Even when exposed to a high temperature, the impurity concentration of the p-type cladding layer and the active layer can be accurately controlled to a desired concentration.

In addition, C present in the diffusion suppressing layer
Means that the diffusion coefficient in GaAs is 2 × 10 2 at 800 ° C.
^Since it is extremely small at about ⁻¹⁶ cm ² / s, C hardly diffuses into the active layer or the p-type cladding layer, and thus, the impurity concentration of the p-type cladding layer and the active layer can be accurately adjusted to a desired concentration. Can be controlled.

Further, according to the semiconductor light emitting device of the present invention, the diffusion suppressing layer as described above can sufficiently suppress the diffusion of impurities with a thickness of only 0.01 μm to 0.2 μm. In addition to being shortened, the light emitting element can emit light with desired luminance at a relatively small voltage, and a semiconductor light emitting device excellent in productivity and luminous efficiency can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a semiconductor light emitting device according to an embodiment of the present invention, and FIG. 2 is a plan view of the semiconductor light emitting device of FIG. 1, where 1 is a substrate, 2 is a light emitting element, and 4 is n.
A type cladding layer, 5 is an active layer, 6 is a diffusion suppressing layer, 7 is a p-type cladding layer, and 10 is a p-type contact layer.

The substrate 1 is formed of a single crystal silicon so as to form a rectangular shape, and a plurality of light emitting elements 2 and the like are disposed on the upper surface thereof along the longitudinal direction. Functions as a material.

The substrate 1 is first formed into a single crystal silicon ingot (lumps) by employing a conventionally known Czochralski method (pulling method) and the like, sliced to a predetermined thickness, and polished the surface. Produced by

The plurality of light emitting elements 2 provided on the upper surface of the substrate 1 are, for example, 600 dpi (dot per inch).
The light-emitting elements are arranged linearly in the longitudinal direction of the substrate 1 at a density of (ch), and a plurality of light-emitting elements 2 constitute a light-emitting element array.

The light emitting element 2 is made of a GaAs compound semiconductor, and includes a buffer layer 3, an n-type cladding layer 4, an active layer 5, a diffusion suppressing layer 6, a p-type cladding layer 7, and a p-type contact layer 10 sequentially. It is formed of a six-layered stacked body that is formed by epitaxial growth.

The n-type cladding layer 4, the active layer 5, the diffusion suppressing layer 6, the p-type cladding layer 7, and the like constituting the light emitting element 2 are doped with predetermined impurities by a predetermined amount for controlling conductivity. The n-type cladding layer 4 has, for example, S
Any one of i, Ge and Sn is 1 × 10 ¹⁷ cm ^{−3 to} 5
× 10 ¹⁸ at a concentration of cm ^-3, the active layer 5, for example Zn, M
g, Cd, or Be is any one of 5 × 10 ¹⁸ cm ^{−3 to} 5
At a concentration of × 10 ¹⁹ cm ^-3 and in the p-type cladding layer 7,
The same impurities as in the active layer 5, that is, Zn, Mg, Cd, B
e is any one of 5 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ cm
^-3 , and these impurities cause n
Each layer of the mold clad layer 4, the active layer 5, and the p-type clad layer 7 is given predetermined conductivity.

A cathode electrode 8 is ohmic-connected to the buffer layer 4 and an anode electrode 9 is ohmic-connected to the p-type contact layer 10, respectively. When a predetermined voltage is applied between the electrodes 8, 9, The electrons in the n-type cladding layer 4 and the holes in the p-type cladding layer 7 are injected into the active layer 5, and these electrons and holes are recombined in the active layer 5. Light is generated.

The diffusion suppressing layer 6 interposed between the active layer 5 and the p-type cladding layer 7 of the light emitting element 2 is doped with C (carbon atom).

C in the diffusion suppressing layer 6 is 5 × 10 ¹⁸ c
The concentration is set to m ⁻³ to 1 × 10 ²⁰ cm ⁻³ , and when these Cs serve as barriers, Zn, Mg, Cd, Be doped in the p-type cladding layer 7 and the active layer 5 are doped. Diffusion of other impurities can be effectively prevented, and the impurity concentration of the p-type cladding layer 7 and the active layer 5 is desired even when the light emitting element 2 is exposed to a high temperature at the time of manufacturing a semiconductor light emitting device or the like. The concentration can be maintained.

In addition, C present in the diffusion suppressing layer 6
Means that the diffusion coefficient in GaAs is 2 × 10 2 at 800 ° C.
^Since C is extremely small at about ^-16 cm ² / s, C hardly diffuses into the active layer 5 and the p-type cladding layer 7. Can be precisely controlled.

Hereinafter, a method for forming the above-described light emitting element 2 will be specifically described.

The light emitting device 2 made of a GaAs compound semiconductor is manufactured by using a conventionally known MOCVD method (Metal Organic Chemistry).
It is formed by adopting ical Vapor Deposition) 2-step growth method and dislocation reduction method by method, as a raw material thereof, trimethyl gallium (TMG), trimethyl aluminum (TMA), etc. arsine (AsH ₃₎ is used. Further, doping of C into the diffusion suppressing layer 6 is as follows.
The test was carried out by using C contained in Group III raw materials TMG and TMA as they were (hereinafter referred to as auto doping).

First, in order to remove an unnecessary oxide film formed on the surface of the substrate 1 made of single crystal silicon, a pretreatment is performed in an arsine atmosphere at a substrate temperature of 800 ° C. to 950 ° C. A buffer layer 3 doped with a predetermined amount of n-type impurities by employing a two-stage growth method.
Is formed to a thickness of 2 μm to 5 μm, and then Al _y Ga _{1 -y} As (0 <y ≦ 0.3) is formed on the buffer layer 3 to a thickness of 0.1 μm to 5 μm.
The n-type cladding layer 4 (carrier concentration: 1 × 10 ¹⁷ cm ^{−3 to} 5 × 10 ¹⁸ c) is grown epitaxially by 1.0 μm.
m ^-3 ), and Al _x Ga _{1 -x} As (0 ≦ x ≦
0.3) is epitaxially grown by 0.1 μm to 1.0 μm to form a p-type active layer 5 (carrier concentration: 5 × 10 ¹⁸ c).
m ^{−3 to} 5 × 10 ¹⁹ cm ⁻³ ), and Al _z G
a _1-z As (0 <z ≦ 0.3) from 0.01 μm to 0.2 μm
m by epitaxially grown by diffusion suppressing layer 6 (carrier ^{concentration: 5 × 10 18 cm -3 ~1} × 10 20 cm -3) is _{formed, Al y Ga 1-y As} (0 thereon further <y ≦ 0 .3)
Is epitaxially grown by 0.1 μm to 1.0 μm to form a p-type cladding layer 7 (carrier concentration: 5 × 10 ¹⁸ cm ⁻³ to
1 × 10 ²⁰ cm ⁻³ ), and finally, a p-type contact layer 10 doped with a predetermined amount of p-type impurities has a thickness of 0.05 μm.
The light-emitting element 2 is formed to have a thickness of about 0.3 μm and thus has a six-layer laminated structure.

The autodoped C in the diffusion suppressing layer 6 is an amphoteric impurity which replaces either the group III atom or the group V atom, and occupies different atomic positions depending on the element type, the substrate plane orientation, or the growth conditions. . That is, by adjusting the supply ratio (V / III ratio) between the group V element and the group III element, it can be used as either a p-type impurity or an n-type impurity. If it is desired to increase p, the group V element exhibiting p-type behavior and III
It is sufficient to reduce the V / III ratio in the range of feed ratios of group elements (V / III ratio), by increasing the V / III ratio in the opposite group V raw material AsH3 (arsine) or AsH ₃ separate Since the hydrogen radicals contribute to the methanation of methyl groups such as TMG and TMA, the concentration of C decreases.

The carrier concentration of the diffusion suppressing layer 6 is also adjusted by the growth temperature, the pressure during the growth, and the like.
The concentration is adjusted to substantially the same (within ± 5%) as the carrier concentration of at least one of the p-type cladding layers 7. TM described above
Decomposition of G and the like is suppressed at lower temperatures and lower pressures to promote C doping, and at higher temperatures and high pressures, promotion of C doping is suppressed.

In this case, since the diffusion suppressing layer 6 as described above may have a thickness of only 0.01 μm to 0.2 μm, epitaxial growth can be performed in a relatively short time, and the light emitting element 2 can be formed with a relatively small voltage. Can emit light at a desired luminance, and a semiconductor light emitting device excellent in productivity and luminous efficiency can be obtained.

In this case, C doped in the diffusion suppressing layer 6 is auto-doped by adjusting the V / III ratio, temperature, pressure and the like of the raw material used during epitaxial growth. , P-type clad layer 7 can be controlled, and there is no large difference in carrier concentration distribution at the boundary between active layer 5 and p-type clad layer 7, and 1 × 1
Even if a large amount of C as much as 0 ²⁰ cm ⁻³ is doped, the activation rate is close to 1, and there is no compensation or formation of a deep level. As a result, a high-performance light-emitting element 2 having good light-emitting characteristics can be obtained.

The cathode electrode 8 connected to the buffer layer 3 of the light emitting element 2 and the p-type contact layer 1
The anode electrode 9 connected to 0 is used to apply a power supply voltage to the light emitting element 2. For example, a laminate of silicon and aluminum is processed into a predetermined pattern by employing a conventionally known photolithography technique and etching technique. Formed by

It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

For example, in the above embodiment, a diffusion preventing layer having the same composition as the diffusion preventing layer 6 may be interposed between the n-type cladding layer 4 and the active layer 5.

In the above embodiment, the light emitting element 2
LED was used as the
(Laser Diode) and VCSEL (Vertical Cavity Surfa)
ce Emitting Laser Diode) may be used.

Further, in the above embodiment, the light emitting element 2 is
Although the epitaxial growth is performed by the OCVD (metal organic chemical vapor deposition) method, other methods such as MB
E (molecular beam epitaxy) may be used for epitaxial growth.

Further, in the above-described embodiment, an electronic circuit such as a transistor or a shift register for controlling light emission of the light emitting element 2 is integrally formed in a region of the upper surface of the substrate where the light emitting element 2 does not exist. 2 may be covered with a protective film made of silicon oxide or the like.

[0039]

According to the semiconductor light emitting device of the present invention, Ga
Between a p-type cladding layer and an active layer of a light emitting device formed of an As-based compound semiconductor, a GaAs-based compound semiconductor is used as a main component, and C is set to 5 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ c.
Since the diffusion suppressing layer containing at a concentration of m ⁻³ is interposed, C in the diffusion suppressing layer acts as a barrier to effectively diffuse other impurities doped into the p-type cladding layer and the active layer. Therefore, even when the light emitting element is exposed to a high temperature at the time of manufacturing a semiconductor light emitting device or the like, the impurity concentration of the p-type cladding layer and the active layer can be accurately controlled to a desired concentration.

In addition, C present in the diffusion suppressing layer
Means that the diffusion coefficient in GaAs is 2 × 10 2 at 800 ° C.
^Since it is extremely small at about ⁻¹⁶ cm ² / s, C hardly diffuses into the active layer or the p-type cladding layer, and thus, the impurity concentration of the p-type cladding layer and the active layer can be accurately adjusted to a desired concentration. Can be controlled.

According to the semiconductor light emitting device of the present invention, the diffusion suppressing layer as described above can sufficiently suppress the diffusion of impurities with a thickness of only 0.01 μm to 0.2 μm. In addition to being shortened, the light emitting element can emit light with desired luminance at a relatively small voltage, and a semiconductor light emitting device excellent in productivity and luminous efficiency can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a semiconductor light emitting device according to one embodiment of the present invention.

FIG. 2 is a plan view of the semiconductor light emitting device of FIG.

FIG. 3 is a sectional view of a conventional semiconductor light emitting device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Light emitting element, 4 ... N-type clad layer, 5 ... Active layer, 6 ... Diffusion suppression layer, 7 ...
p-type cladding layer

Claims (4)

[Claims] 1. The method according to claim 1, wherein the upper surface of the substrate made of single crystal silicon is
What is claimed is: 1. A semiconductor light emitting device comprising a light emitting element comprising an aAs-based compound semiconductor and sequentially stacking an n-type cladding layer, an active layer and a p-type cladding layer, wherein the p-type cladding layer of the light-emitting element-active GaAs between layers
Semiconductor light emission characterized by interposing a diffusion suppressing layer containing a compound semiconductor as a main component and containing carbon atoms (C) at a concentration of 5 × 10 ¹⁸ cm ⁻³ to 1 × 10 ²⁰ cm ^−3. apparatus. 2. The semiconductor light emitting device according to claim 1, wherein the compound semiconductor forming the diffusion suppressing layer is Al _x Ga _{1 -x} As (0 <x ≦ 0.3). 3. The thickness of the diffusion suppressing layer is 0.01 μm or more.
3. The semiconductor light emitting device according to claim 2, wherein the thickness is 0.2 μm. 4. The method according to claim 1, wherein the impurity doped in the active layer and the p-type cladding layer is any one of Zn, Mg, Cd, and Be.
4. The semiconductor light emitting device according to claim 1, wherein the device is made of a seed.