JPS5947478B2 - Semiconductor light emitting diode and manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and more particularly to a semiconductor light emitting diode and a method for manufacturing the same.

The present invention can be most effectively used in semiconductor injection luminescent devices, light emitting diode devices, digital alphanumeric displays, and other data display devices. It is based on a GaAlAs solid buttress simultaneously doped with Zn and Te, with a large bandcap layer (approximately 2 μm) on top of the thin active layer of the solid body.
Semiconductor light emitting diodes are known in which the semiconductor light emitting diode is grown to a certain thickness (thickness) to ensure transmittance for emitted light.

However, in order to be able to make contact, another layer of GaAs must be added to the surface thus obtained. Mi
she9G9Schue Electronics Letter (E
lectrOnicsLetter), 8, 1, 16-
17, 1972).

The inherent drawbacks of conventional light-emitting diodes include the lack of a compensating active layer that prevents the reduction in light generation due to self-absorption within the semiconductor, and the lack of a final GaAs layer that is thin enough to absorb a small amount of recombined emission. exists.

The best light emitting diode has an I-electron efficiency of 300 amps K'('0
．． It is 3%. The manufacturing method of semiconductor light emitting diodes is based on a liquid phase epitaxial method, which is carried out in the presence of two types of additives (Zn and Te) in a Ga melt containing Al saturated with arsenic. Are known.

During the growth process? By varying the cooling rate of the melt, the segregation coefficients and their ratios change, so that the epitaxial layer alternates between different conductivity types during the growth process. The disadvantages of this method are that it is impossible to obtain a supplementary active layer and that it is not possible to generate high-intensity light with high efficiency.

p+ type GaAs substrate and Zn doped GaAlas
Single-crystal epitaxial p-layer and Te-doped G
Other semiconductor light-emitting diodes are known with epitaxial layers of single crystal solid aAlAs and hederojunctions between these epitaxial layers.

This epitaxial layer is practically doped to the same concentration level. However, this semiconductor light emitting diode cannot be manufactured by any of the known methods.
Therefore, the present invention aims to eliminate the above-mentioned drawbacks. Is this invention a reunion? It is an object of the present invention to provide a semiconductor light emitting diode having a compensation layer, which has high luminous efficiency and luminance, and a method for manufacturing the same.

In order to achieve the above object, a semiconductor light emitting diode according to the present invention has a p+ type GaAs substrate and a concentration of 4X1017 to 3X.
1018C:! An epitaxial p-layer of a single-crystal solid body of GaAlA8 doped with Zn to about IL-3 and elongated on the substrate; A compensating P layer of a single crystal solid state of GaAlAs doped with Znl, Te to an extent of 6 and a concentration of 6×1
GaA doped with Te to about 0P7~5X1018
and an epitaxial n-layer of a single crystal solid body of lAB,
The compensation P layer has a thickness approximately corresponding to the diffusion length of the injected charge carriers, and a heterojunction is formed between the compensation RlLP layer and the epitaxial n layer. The layer is preferably grown on a portion of the compensation layer.

The epitaxial n-layer may hold an epitaxial n+ layer, and it is preferable that the n+ layer is grown on a portion of the epitaxial n-layer.

It is convenient to grow the n'++ layer partially on top of the epitaxial n+ layer. The presence of the n+ layer reduces the series resistance of the di-semiconductor diode and improves the mobility of charge carriers in that layer.

Further, due to the presence of the n-layer, reliable ohmic contact can be achieved without performing any other operations on the growth of this layer. It is convenient to attach one ohmic metal contact to the surface of the last epitaxial layer and the other ohmic metal contact to the substrate.

In addition, in order to achieve the above object, the method for manufacturing a semiconductor light emitting diode according to the present invention includes a GaAs substrate, a first Ga liquid phase containing Al saturated with arsenic and containing Zn and Te, and a second Ga liquid phase containing Te. A first liquid phase doped with Zn and Te was brought into contact with the substrate to grow an epitaxial p-layer of the diode structure with a controlled thickness. leaving a layer of said first liquid phase on said substrate; said second liquid phase containing Te is brought into contact with said layer of controlled thickness such that the thickness corresponds to the diffusion length of the injected charge carriers; with a compensation P layer. It is characterized by growing epitaxial n-layers alternately.

In order to grow the epitaxial n+ layer, it is convenient to speed up the crystallization of the second liquid phase by a factor of 15-30.

In order to grow the n-layer, the crystallization of the second liquid phase should preferably be further accelerated by a factor of 2-3.

Embodiments of the present invention will be described below with reference to the accompanying drawings. The semiconductor light emitting diode of the present invention includes a p+ type GaAs substrate 1,
It has epitaxial layers 2 and 3.

The epitaxial layers 2 and 3 are doped to approximately the same concentration level. The epitaxial p layer 2 has a luminance of 0.4×101
It is a single crystal solid solution of GaAlAs doped with Zn to about 8 to 2 x 1018 cm-3. It has a thickness of 16-38μ.

Also, the epitaxial n-layer 3 has a concentration of 0.6×1018~
A single crystal solid body of GaAlAs doped with Te to the extent of 5x1018c1rL'-3, with a thickness of 2 to 26μ. A heterojunction 4 is formed between layers 2 and 3. The diode according to the invention also has an epitaxial n
GaAl doped with Zn and Re to the same concentration as layer 3
It comprises a compensation layer 5 of a single crystal solid solution of As.

The supplementary injection layer 5 is sandwiched between the epitaxial layers 2 and 3 and its thickness corresponds to the diffusion length of the charge carriers injected into the n-layer. It is known that the diffusion length of the injected charge carriers varies depending on the type of semiconductor D) can be determined by any known method. is provided.

These contacts may be made of aluminum, nickel, copper, silver, tin, gold, and alloys based on these metals. These metal contacts are deposited in place by a suitable method and exhibit ohmic properties as soon as they are deposited.

The presence of the supplementary injection layer 5 of the diode according to the invention increases the luminescent recombination.

This luminescent recombination is based on the fact that there is a spread v in the density of states in the compensation layer in which the injected charge carriers recombine. This also results in a significant reduction in the self-absorption of radiation in the semiconductor material of the diode. In Figures 1, 2, and 3, . The epitaxial n-layer 3 covers the entire surface of the compensation layer 5; in the diode structure shown in FIG. 4, the epitaxial n-layer 8 covers only a part of the compensation layer 5.

Epitaxial n layer 3 (8) is epitaxial n+ layer 9
(Figures 2 and 3).

This n+ layer is composed of a single crystal solid solution of GaAlAs doped with Te, and its charge carrier concentration is 0.8×10
18~8.0×1018]-3, and the thickness is 4~8μ. The composition of this layer is arbitrary with respect to AlAs. Second
, 3, the n+ layer 9 covers the entire surface of the n layer 3,
It can also be seen that the entire surface of the n-layer 3 covers the entire surface of the auxiliary layer 5.

On the other hand, in the structure shown in FIG. 5, the n+ layer 10 covers only a portion of the n layer 3. In Figures 6 to 11, the n-layer 8 only partially covers the auxiliary injection layer 5 (Figures 6, 1, 10, and 11). n+
Further embodiments of semiconductor light-emitting diodes are shown in which the layer 10 covers the entire surface (FIG. 6) or only part of the surface (FIGS. 1, 8, 9, 10, 11) of the n-layer 8. Due to the presence of the n+ layer, the series resistance of this light emitting diode is low and the mobility of the internal charge carriers is high.

According to the invention, this light emitting diode has an epitaxial Nlf layer 11 (FIG. 3) overlying the epitaxial N+ layer 9.

This Nlf layer 11 is constructed based on a single-crystal solid body of GaAlAs doped with Te, and its charge carrier concentration is 0.3 x 1010 to 1.0 x 1019 cm-3, and its thickness is 10 to 20 μ. Its composition with respect to AlAs is arbitrary. Nlf layer 11 is n+ layer 9 (10)
Cover the entire surface (Figures 3, 9, and 10) or part of it (Figure 11).

A further ohmic metal contact 6 is deposited on top of the Nff layer 11.

The presence of this red layer increases the reliability of the contact 6 and simplifies its attachment. FIG. 12 is a perspective view showing the structure of FIG. 10 to fully illustrate the features of the light emitting diode of the present invention.

In order to better understand the present invention, a special example embodying the semiconductor light emitting diode of the present invention is shown below.

Example 1 This diode has the following layers.

1. p+ type GaAs substrate: charge carrier concentration Np = 8x
1018cm-3, direction [100]+51, Hall mobility Up=120cm2/Vsec・2. Epitaxial p layer: Np=1018cnL-3, thickness d224μ, A
lAs-containing 1 approx. 34 atoms.
X1017c1n-3, d22μ, AlAs containing 12 about 43 at%, 4. Ebitaxial n layer: electron concentration Ne=
2 x 1018 cm-3, d-14μ AlAs content 2 about 43 at%.

The characteristics of this light emitting diode are as follows.

Emission energy Eev:= 1.85ev, external quantum efficiency r2 1.2%, current density j 0A/d, emission brightness B=
5000cd/M2. Example 2 1. Pf type GaAt substrate: 2×10, 19I-3, direction [100] ±30', Up=80cwL2/Vs
ec,2. Epitaxial p layer: Np=1018c7n
-3, d = 18μ, AlAs content = approximately 32 at%, 3
．． Compensation p layer: Np=5×1017cTn-3, d2μ
, AlAs content 1=approximately 32 atomic %, 4. Epitaxial d Kyoji Ne=2×1018c7nH, d=16μ, Al
As content 1=45 at%.

Diode characteristics: Eev 1.83ev, r = 0.8
Cf6,B=3200cd/M2(j=10
Person/Employment 2).

Example 31. P+ type GaAs substrate: Np=4×1019c!
n-3. Direction [100] ±10up265d/Vsec
2. P layer: Np22×AOl8cwL-3, d=24
μAlAs content 1=approximately 34 atomic %, 3. Fuhama p layer: Np
23X1017CffL-S, d=1.5μ, AlAs
Concentration content = approximately 34 at%, 4. n layer 2 Ne=7×1017
c! n-3, d=12tbA1As content=approximately 45 at%, diode characteristics: Eev=1.85ev, r=0
．． 5%, B = 2600cd/CTn2 (j = 1
0A/CfrLZ)゜Example 4 1. Pf type GaAs substrate: Np=2×1019c1n
-3 directions [100] ±30', Up=105c! nshiV
sec, 2. P layer: 3×1018C1rL-3, d=
32 μ, about 32 atom % AlAs-containing silicate, 3. Compensation p layer: Np=4×1017 (V7l-3, d=2μ, AlA
S content: approximately 34 at%, 4. n layer: Ne=1018c
! n-3, d2 18μ, AlAs content = approximately 44 at%
.

Diode characteristics: Eev half 1.83ev, r=0.7"
, B = 2000cd/M2 (j = 10A/1).

Example 5 1. P+ type GaAs substrate: Np2 1018c! n-3,
Direction [100] ±5', Up 2140 2/V8ec,
2. P layer: Np23×1018C! RL-3, d=18
μ, AlAs content 1=approximately 35 atomic %, 3. Fuhama p layer: N
pni7×1017C1n-3, d=2μ, AlAs content=approximately 35 atoms Q6, 4. n-layer: Ne=7 x engineering 017c
m-3, d = 14μ, AlAs content 12 approximately 42 at%
, diode characteristics: Eev=1.85ev, r:0.8
%, R Nini 4200cd/M2(j 2IOA/(V7
l2).

Example 6 The substrate, p-layer, compensation layer, and n-layer are the same as in example 3, and in addition 5. Ebitaxial n+ layer: charge carrier concentration Ne+=approximately 1018C7n-3, thickness -4μ, 6. Epitaxial layer n-layer: Charge carrier concentration Nelf=
Approximately 4×1018c1n-3, thickness=12μ, 7. The n+ layer and Nlf layer are etched using an etching agent (H2g) 4:H2O2:H
2O=3:l:1).

8. Ohmic contacts are nickel.

The characteristics of this diode are the same as in Example 3.

Example 71. P+ type GaAs substrate: Np = 4 x 1019 cm
-3, direction [100] ±5', UP2 100cTn2/
Vsec, 2. p layer: Np::1018cwL-3,d
=26μ. AlAs content: 12 about 34 atom %.

3. Compensation layer: Np::5×1017cnL-3, d=2
μ, AlAs content = approximately 34 at%, 4. n layer: Ne:
:2×101ac! n-3, d=12μ, AlAs content=approximately 43 at%, 5. Epitaxial n+ layer: d=
6μ. Ne+ki4X1018CfIL-3.6. 7. The n+ layer is partially removed by etching agent (H2SO4:HzO, 21:1). The contact points are made of gold.

Example 8 substrate. The p-layer, compensation layer, and n-layer are the same as in Example 4.

5. Epitaxial n+ layer: d2 4μ, Ne 3×1
0. ．． 18cm-3,6. Epitaxial n-well layer: d
210μ, Nelf=6×1018c7n-3,7. n
Tanlayer is an etching agent (112S04:H2O!:H2
04:1:1), the recombined emission passes through the n and n+ layers.

8. The ohmic contacts are made of tin.

Diode characteristics: Eve 1.83ev, r2 0.8%
, B = 3100cd/'M2 (j = engineering 0A/C
? -112).

Example 9 The substrate, p layer, compensation layer, n layer, and n+ layer are the same as in example 6.

6. Epitaxial n'1f layer: d: 16μ, Nel
f==6×1018CTfL-3,7. n+ and Nl
The f-layer is partially removed using an etching agent (H2SO4:H2O2=Ellie).

8. The ohmic contacts are made of aluminum.

Diode characteristics: Eev-=1.85ev, r=0.6
%, B = 2900cd/'M2 (j = 10A/C
7n2). Example 10 Substrate, p layer, compensation layer, and n layer are the same as example 5, 5
．． n+ layer: d=8μ, Neo 1018cwL-3, recombination light emission passes through the n layer and the n+ layer.

6. The ohmic contact is made by melting an Au:Ge 297:3 alloy at a temperature of 560°C.

Diode characteristics: Eev2-1.85ev, r-:0.
9%, B = 4000cd/M2 (j = 10A
/Cm2).

Example 11 1. p+ type GaAs substrate: Np=5×1019cm1,
[100] ±30', Up=130 (Vll? /Vs
ec,2. P layer: Np Ki2X1018 field 1-3, d=2
2μ, AlAs content=approximately 34 at%, 3. Compensation layer: N
p hand 6×1017cm-3, d=2μ, AlAs content 1
Approximately 34 atom%, 4. N layer: Neki 4X1018 (hiring-3
, d=16μ, AlAs content=about 47 at%, 5. n
+ layer: Ne half 8X1018c! n-3, d=8μ, 6.
The n+ layer is partially removed using an etching agent (H2SO4:H2O2=3:E).

7. The contact points are made of gold.

Diode characteristics: Eev 1.84ev, r 0.9%
, B2 3900cd/M2 (j=IOA/I.

less than. Manufacture of semiconductor diode according to the present invention. Explain the construction method. First, a GaAs substrate and an arsenic-saturated A
Two types of liquid phases of Ga containing l are used.

The manufacturing process is carried out in an open system in a stream of pure hydrogen. A graphite magazine is used as a charge container, which magazine contains the GaAs substrate and the molten material for epitaxial layer growth. A GaAs substrate is placed within a compartment of the magazine. The composition of the casting member for growing the p layer and supplementary injection layer of the single crystal solid solution (first liquid phase) is as follows.

Ga:5.0+0.19GaAs:480+40m1A
1:11.6+0.4mgZn:22+4m9Te:0.07+0.01mθ The composition of the casting member for growing the n-layer of the single crystal solid solution (second liquid phase) is as follows.

Ga:5.0+0. Engineering GaAs: 580+ 40? N9 Al: 15.6 + 0.6 mg T e2 2.2 + 0.3 mj::r The manganese containing the substrate and molten material is placed in a quartz reaction vessel.

Purified hydrogen is flowed through the reaction vessel to a dew point of (60-Fl5)C. Such a magazine is kept horizontal in a constant temperature field of 960+5°C. To achieve saturation in the molten material (liquid phase), the magazine and its contents are kept at a constant temperature for 30-40 minutes, and then the first liquid phase is brought into contact with the substrate by manipulating the magazine.

When the contact is made, the program cooling device is activated and the temperature reaches 0.
Cool at a cooling rate of 3-0.5°C/Min. 12
When cooled by a temperature of ~20℃, epitaxial
The layers grow.

When this epitaxial layer grows. ．． 300-500
A μ-thick layer of the first liquid phase is left on the substrate. Further, the second liquid phase is brought into contact with the first liquid phase layer immediately. Accompanying this operation is the apparent growth of a compensating p-layer. Furthermore, 16-34℃
When the inside of the reaction vessel is cooled by a certain temperature, an epitaxial n-layer grows after the auxiliary injection p-layer.

Next, increase the cooling rate by 15 to 30 times to increase the epitaxial n.
+ layer is grown, and finally the epitaxial n+ layer is grown with the crystallization speed further increased by a factor of 2-3. The final stage of this process
) Partially or completely removing the melt from the VC substrate.

Example 12 P-type GaAs is used as the substrate material.

The composition of the prefecture liquid phase is as follows.

The composition of the second liquid phase is as follows.

The structure of this semiconductor diode is grown as described above under the following conditions.

The manufacturing process is carried out at a temperature of 963° C. and the magazine with its contents is maintained at this temperature for 30 minutes.

The cooling rate after bringing the first liquid phase into contact with the substrate is 0.3℃/
It is Min. The cooling temperature for growing the p layer is 96
The temperature is 3 to 945°C. The thickness of the first liquid phase layer formed on the substrate is 450μ. The second liquid phase is brought into contact with the first liquid phase layer at a temperature of 945°C, and then the system is further cooled by a temperature of about 24°C at a cooling rate of 0.3°C/Min. grows.

After the n-layer is grown, the cooling rate may be increased by a factor of 2 to 3 to grow the epitaxial n+ layer.
It becomes possible to grow an epitaxial n+ layer.

It takes only a few minutes to grow the last two layers.
The semiconductor light emitting diode of the present invention has the characteristics of high recrystallized luminous efficiency, high luminous luminance, and low series resistance because the impurity concentration is kept low.

Due to the presence of the n-th layer, highly reliable ohmic contacts can be obtained without requiring any additional operations for the attachment of ohmic contacts. Although the present invention has been described in detail above, the main embodiments of the present invention are listed below. 1. The diode according to claim 1, wherein the epitaxial n-layer is grown on a portion of the surface of the compensation layer.

2. A diode according to claim 1 or claim 1, wherein the epitaxial n+ layer is grown on the epitaxial n layer.

3. The diode according to item 2 above, wherein the epitaxial n+ layer is grown on a portion of the epitaxial n layer.

4. The diode according to item 2 or 3 above, wherein the epitaxial n+ layer is grown on the epitaxial n+ layer.

5. The diode according to item 4 above, wherein the epitaxial n+ layer is grown on the epitaxial n+ layer.

6. A diode according to claim 1 and claims 1 to 5, characterized in that an ohmic metal contact is provided on the last epitaxial layer.

1. A diode according to claim 1 and claims 1 to 6 above, in which an ohmic contact is formed on a substrate.

8. A method according to claim 2, wherein the epitaxial n+ layer is grown by increasing the crystallization rate of the second liquid phase by 15 to 30 times.

9. In the method described in item 8 above. A method in which the epitaxial n+ layer is grown by increasing the crystallization speed of the second liquid phase by two to three times.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a semiconductor light emitting diode of the present invention, FIG. 2 is a vertical sectional view of a semiconductor light emitting diode of the present invention having an n+ layer, and FIG. 3 is a semiconductor light emitting diode of the present invention having an n+ and n layer. FIG. 4 is a longitudinal section through a semiconductor light-emitting diode of the invention with an epitaxial n-layer grown on a portion of the compensation layer; FIG. FIG. 6 is a longitudinal cross-sectional view of a semiconductor light-emitting diode of the present invention having an n+ layer grown on a portion of the n+ layer; FIG. 8 is a longitudinal cross-sectional view of a semiconductor light emitting diode of the present invention having an epitaxial n-layer grown on a part of the compensation layer and an n+ layer grown on a part of the n-layer, and FIG. FIG. 9 is a vertical cross-sectional view of a semiconductor light emitting diode of the present invention having an n+ layer grown on a part of the n+ layer and an n+ layer grown on a part of the n+ layer. FIG. 10 is a vertical cross-sectional view of a semiconductor light emitting diode of the present invention having an n'l+'' layer, an n layer grown on a part of the compensation layer, an n+ layer grown on a part of the n layer, and an n+ layer grown on a part of the n layer. FIG. 11 is a vertical cross-sectional view of a semiconductor light emitting diode of the present invention having an n layer grown on a part of the compensation layer, an n+ layer grown on a part of the Nn layer, and an n+ layer grown on a part of the Nn layer.
FIG. 12 is a longitudinal cross-sectional view of a semiconductor light emitting diode of the present invention having an n-layer grown on a part of the compensation layer, and a part of the n-layer grown on a part of the compensation layer. n+ grown above
FIG. 2 is a perspective view of a semiconductor light emitting diode of the present invention having an n+ layer and an n+ layer. 1...Substrate, 2...Epitaxial p-layer, . 3...Epitaxial n-layer, 4.
...heterojunction, 5...auxiliary injection layer, 6,1
...Ohmic metal contact, 8...Epitaxial n-layer. ．． 9, 10...Epitaxial n+ layer, 11...Epitaxial n+ layer.

Claims (1)

[Claims] 1 P^+ type GaAs substrate and a concentration of 4 x 10^1^7~
An epitaxial p-layer of a GaAlAs single-crystal solid solution doped with Zn to about 3 x 10^1^8 cm^-^3 and grown on the substrate; ^7~7x10^1^7cm
GaAlAs doped with Zn and Te to about 3
A compensating P layer of a single crystal solid solution of GaAlAs, and an epitaxial N layer of a single crystal solid solution of GaAlAs grown on the compensating P layer and doped with Te to a concentration of about 6×10^1^7 to 5×10^1^8. A semiconductor light emitting diode comprising: the compensating P layer having a thickness substantially corresponding to the diffusion length of injected charge carriers, and forming a heterojunction between the compensating P layer and the epitaxial N layer. 2 A GaAs substrate, a first Ga liquid phase containing Al saturated with arsenic and containing Zn and Te, and a second Ga liquid phase containing Te.
A first liquid phase doped with Zn and Te is brought into contact with the substrate to grow an epitaxial layer of the diode structure, and the epitaxial layer of the diode structure is grown with a controlled thickness. leaving a layer of a first liquid phase on the substrate; a second liquid phase containing Te in contact with the layer of controlled thickness, having a thickness commensurate with the diffusion length of the injected charge carriers; A method of manufacturing a semiconductor light emitting diode, which sequentially grows a compensating P layer and an epitaxial N layer.