JPS5987881A - Manufacture of optical semiconductor device - Google Patents

Abstract

PURPOSE:To make thickness to the degree of 300mum, and to enhance yield of the progress of manufacturing work of a light emitting element by a method wherein after an N type Ga1-xAlxAs epitaxial growth layer added with tellurium or silicon is grown on an N type GaAs substrate, an N type and a P type Ga1-yAlyAs (x>y) epitaxial growth layers added with silicon and added with the small quantity of Al are grown in order. CONSTITUTION:An epitaxial growth solution of Ga1-xAlxAs added with tellurium is made to come in contact with the upper part of a GaAs substrate 1 added with N type silicon at the temperature of 950 deg.C to be cooled to 850 deg.C by the rate of 1 deg.C every one minute, and an N type Ga1-xAlxAs growth layer 2 is grown. Then the temperature is risen again up to 920 deg.C in the condition that the used epitaxial growth solution is removed from the upper part of the GaAlAs growth layer 2, and it is held as it is till the temeprature is stabilized. Then an N type Ga1-xAlyAs growth layer 3 added with silicon and a P type Ga1-yAlyAs layer 4 are grown on the N type Ga1-xAlxAs growth layer 2 cooling the Ga1-yAlyAs (x>y) epitaxial growth solution added with silicon to 700 deg.C, and P- N junction is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing an optical semiconductor device made of GaAtAs and made of bamboo suitable for use as a high-output light emitting diode in the infrared region. [Technical background of the invention and its problems] Light-emitting diodes used in photocouplers, optical communication sensors, etc. are mainly made of silicon, which is an amphoteric impurity, on an N-type GaAs substrate by a liquid phase epitaxial slow cooling growth method. is added to grow N-type and P-type GaAs growth layers to form a PN junction. In this case, although the energy of the light emitted from silicon is lower than the forbidden band width of GaAs, the emitted light is largely absorbed in the GaAs layer, and the amount of light actually extracted to the outside of the light emitting element is small. On the other hand, as an element for effectively extracting light emitted inside to the outside, there is an element using GaAtAs as shown in FIG. In this case, the temperature grogram shown in Figure 2 shows that N-type Ga
On the As substrate, silicon, which is an amphoteric impurity, is added to GaAtAs using a liquid phase epitaxial slow cooling method to form N-type +
A P R'i-GaAtAs growth layer is grown to form a PN junction. However, in FIG. 2, a indicates the point of contact between the GaAs substrate and the epitaxial solution. However, in the case of the structure formed as described above, the segregation coefficient of At is large at high temperatures and becomes small at low temperatures, so the mixed crystal ratio of AtAa in the growth layer increases toward the surface of the growth layer as shown in Figure 1. becomes extremely small. Therefore, most of the light emitted from the PN junction is absorbed on the surface of the GaAs substrate and the growth layer of AtAs with a low mixed crystal ratio, and only the light from the sides is extracted to the outside of the device, resulting in an extremely low level of light. Therefore, in general, the GaAs substrate is removed and the AtA layer in the light emitting region shown in Fig. 1 is grown using only a liquid phase epitaxial growth layer.
N with a high AtAs mixed crystal ratio that absorbs less light than the s mixed crystal ratio
By effectively extracting light from the mold growth layer side to the outside,
A high output device several times higher than that of a GaAs light emitting device is obtained. Note that the emission wavelength is determined by the growth start temperature and epitaxial growth. Furthermore, in conventional multilayer growth, the growth solution is replaced many times during slow cooling, but it is not possible to substantially increase the thickness of the growth layer. This method allows thin layers to be grown with precision. However, although the conventional silicon-doped GaAtAs element can provide high output power, it has drawbacks in terms of manufacturing technology. This is due to the characteristics of the light emitting device as shown in Figure 1 and Figure 2.
In order to effectively extract light from the side where the forbidden band width is wide, it is necessary to remove the GaAs substrate. In the conventional liquid phase epitaxial technology using slow cooling method, the thickness of the multilayer is 2.
The limit is around 00μ. In general, in the manufacture of light emitting devices, 3
Since a growth layer of around 200 μm is required, a large area cannot be treated with a grown layer of around 200 μm, resulting in extremely low yield in the light emitting device manufacturing process. [Object of the invention] The present invention has been made in view of the above-mentioned circumstances, and includes increasing the thickness of the liquid phase epitaxial growth layer by the above-mentioned slow cooling method,
It is an object of the present invention to provide a method for manufacturing an optical semiconductor device that can reduce the thickness to about 300 μm, significantly improve the yield of the light emitting device manufacturing process, and without impairing the characteristics of the light emitting device. It is. [Summary of the invention] The present invention uses a one-time liquid phase epitaxial growth method to grow N-type G
N-type Ga doped with tellurium or silicon on an aAs substrate.
After growing the I
1-2 On the ALzAs growth layer, silicon-added N,
P m Ga1 yA2yAs (x) y) The epitaxial growth layers are sequentially grown so that the growth layers necessary for the light emitting device manufacturing process are formed, and the light emitting device characteristics are also equivalent or better. [Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. Third
4 is a structural diagram of the same example, and FIG. 5 is a temperature program of the process of obtaining the same structure. That is, on a GaAs substrate 1 doped with N-type silicon having an (ioo) plane, a temperature of 950° C.
A tellurium-added Ga1-XAtXA8 epitaxial solution (Ga, GaAs *At) was brought into contact with the 8
Cool to 50°C at a rate of 1°C per minute to form N-type Ga1□
AtxAs growth layer 2 is grown. In Figure 5, b
indicates the point of contact between the GaAs substrate 1 and the silicon-added GaAtAB epitaxial solution. Thereafter, the epitaxial solution used above is removed from above the GaAAAs growth layer 2 as shown in FIG. In that state, 920℃ again
and hold for 1 hour until the temperature stabilizes. Next, Ga1'-yAtyAs (x>y) with silicon added
epitaxial growth solution (Qa, GaAs *At
) at point d in Figure 5, and while cooling to 700°C at a rate of 1°C per minute, the N-type Ga 1
-1ALzAs growth rfA 2 N-type Ga 1-yAtyAs growth layer 3 with silicon added, P-type Ga1-y
A/yAs(x>y) Growth N4 is grown to form PNN
Form a junction. The AtAs mixed crystal ratio distribution is as shown in FIG. 4, and the AtAs mixed crystal ratio at the end of the first grown layer 2 is higher than the AtAs mixed crystal ratio at the beginning of the second grown layer 3. Due to this growth, the thickness of the eviaxial growth layer is 3
A sample of 50μ was obtained with good reproducibility. As another example, a GaAtAs growth layer with silicon added instead of tellurium was grown at 950° C. to 850° C., and a grown layer with a thickness of 350 μm was obtained. At this time, the AtAs mixed crystal ratio distribution and temperature program are the same as in the previous embodiment. According to the above embodiment, a growth layer with a thickness of 300 μm or more can be stably obtained, and the thickness after removing the GaAs substrate 1, which has been a problem in the production of light emitting devices, is sufficient, and the production yield can be improved. will improve. That is, the production yield in the conventional technology was about 20%, but it was improved to about 80% by the present invention. Further, as shown in FIG. 5, when a current of 100 mA was applied in the forward direction and changes in the light emission output were examined, a large difference in the light emission output was observed. This is because in the conventional technology, it is not possible to increase the surface donor concentration of the N-type GaAtAs layer due to the correlation between the luminous efficiency and the St concentration, so the resistance between the surface of the GaAtAa layer and the electrical contact becomes high. This is because the element generates a lot of heat and is thought to cause more deterioration due to heat.In contrast, in the present invention, the first layer of N IJI GaAtA and the s layer 2 of Te
Alternatively, by changing the amount of St added, the surface donor concentration can be made high, and the resistance between the surface and the electrode can be lowered. Therefore, there is very little deterioration due to element heat generation. Furthermore, in the conventional technology, since the thickness of the light emitting element is thin, the rise of the non-quaternary conductive paste due to mount bonding has an adverse effect on the PN junction, and the stress and strain caused by the impact can cause many defects near the PNJg during energization. occurs, causing deterioration in current flow. Therefore, it has been found that the present invention has an effect on deterioration caused by current conduction because the element thickness is large. [Effects of the Invention] As explained above, according to the present invention, it is possible to provide a method for manufacturing an optical semiconductor device which has advantages such as an increase in element thickness, improved manufacturing efficiency, and no deterioration due to electrical conduction. be.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the configuration and characteristics of a conventional optical semiconductor device, FIG. 2 is a diagram showing a temperature grogram of the process of obtaining the same configuration, FIG. 5 is a diagram illustrating the characteristics of the same configuration, FIG. 5 is a diagram showing a temperature program in the process of obtaining the same configuration, and FIG. 6 is a diagram showing the light emission characteristics of the same configuration. 1 ・N-type GaAs substrate, 2 ・N-type Ga 1-, X
AtzAs layer, 3--- N m Ga1 , Aty
As layer, 4.P-type Ga1, AtyAs layer. Applicant's agent Patent attorney Takeshi Suzue Hikodate Figure 1 Figure 2 v1 Open Figure 3. Fig. 4 Fig. 5 Fig. 6 Listen to the crowd

Claims (2)

[Claims] (1) N-type Ga is grown by liquid phase epitaxial growth using slow cooling method.
N-type Ga1 doped with tellurium or silicon on an As substrate
After growing the zALzzjJ1 growth layer, the liquid phase epitaxial growth solution containing tellurium or silicon is removed, and the temperature is raised again in that state to form the N-type Ga 1-
XA! +N-type Ga1 with silicon added on the growth layer, At
yAs growth layer and silicon-added P-type Ga on the growth layer
1-yALyAs growth layer is grown, and the X
A method for manufacturing an optical semiconductor device, characterized in that the relationship between and y is x>y. (2) Said silicon-added P-type Ga 1-yALyA
2. The method of manufacturing an optical semiconductor device according to claim 1, wherein after forming the s-growth layer: the N-type GaAs substrate is removed.