JPS61136997A - Manufacture of p type gallium arsenide single crystal - Google Patents

Abstract

PURPOSE:To obtain a single crystal suitable for an optical device substrate, etc. and wherein p type impurities are uniformly dispersed by using a GaAs melt added with p type impurities and In when a p type GaAs single crystal is manufactured by a liq. sealant rotary pulling method. CONSTITUTION:Ga, As, p type impurities (e.g., zinc), and In 0.1-1,000 times the number of the added p type impurity units are packed in a cylindrical heat-resistant crucible, etc., and a sealant (e.g., B2O3) is further added. The crucible is then arranged in a high-pressure vessel which is pressurized by an inert gas, then the crucible is heated, and the crystal material melt and the sealant melt are separated into two layers. Subsequently, a crystal-pulling shaft provided above the crucible is lowered, a seed crystal attached to the leasing end of the shaft is brought into contact with the crystal material melt, and then the crystal-pulling shaft is lifted while being rotated to grow an electrically conductive GaAs crystal wherein p type impurities are uniformly dispersed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing p-type gallium arsenide (GcLA8) single crystal, and more specifically, it is suitably used as a substrate for optical devices such as semiconductor lasers and light emitting diodes. p
The present invention relates to a method for producing a conductive gallium arsenide single crystal.

(Prior Art) Among the (1)-v group compound semiconductors, GcLA8 has high electron mobility and is being widely used as substrates for ultrahigh-speed integrated circuits, electronic devices, optical devices, etc.

In order to use a GαA8 single crystal as a substrate for an optical device as described above, it is necessary to add n-type impurities or p-type impurities to make it conductive, and the p-type impurities include zinc <
zn) is commonly used.

The method for manufacturing this p-type GαA8 single crystal is LEC.
law is used. This LEC method has excellent features such as a fast crystal growth rate and the ability to obtain large-diameter crystals, but it also has the disadvantage that the grown crystals have many dislocations and that the added impurities do not grow evenly. It has problems such as not being dispersed to other parts of the world.

(Problems to be Solved by the Invention) As mentioned above, if a GaAs single crystal is manufactured by the IEC method, the crystal growth rate is fast and a circular wafer with a large diameter can be easily obtained. When a p-type impurity such as Zn is added to the crystal raw material melt and the crystal is pulled to be used as a substrate for an optical device, boron oxide (Byes
), the added Z
Additives such as S are gettered at B, 0° and are not evenly dispersed in the growing GaAs single crystal. Because the conductivity varies depending on the location of the wafer, the characteristics of the optical device also vary, resulting in low yields and
Device reliability also decreases.

This invention was made in view of the above, and it is a p
It is an object of the present invention to provide a method for easily producing a type GαM single crystal with good reproducibility.

(Means to Solve the Problems) The method for producing a p-type Gaps single crystal according to the present invention uses GaA to which p-type impurities and indium are added as a crystal raw material melt in a liquid-sealed rotational pulling method.

It is characterized by pulling the crystal using a melt.

Regarding the amount of p-type impurity and Is added to the GaAg melt, Z? Using S, melt 1d Todoroki Z
Change the amount of n added in the range of 0.1 to 100 x 10'',
A single crystal was grown by the LEC method using the G, A, and melt to which the above k and I?L were added, varying the amount of crystals added in the range of 0 to 5000 x 10''. As a result of forming an infrared light emitting diode using a wafer cut from a single crystal as a substrate and measuring the luminous efficiency, the results shown in the attached drawing were obtained.In other words, the numerical values shown in the table of the drawing indicate the luminescence efficiency. Efficiency is shown, and where no numerical value is displayed, it means that the diode using the single crystal as a substrate did not emit light.

As is clear from this table, the Zfi content is 0.5 to 5.
A light-emitting diode using a crystal as a substrate in the range of oxio/d emits light;
The light emitting efficiency of the diode is improved by adding in the range of /-. As mentioned above, it is effective that the amount of In added is about 0.1 to 1000 times the amount of p-type impurity added.

The operating conditions for crystal pulling of the LEC method applied to this invention are the same as the general conditions for crystal pulling of GaAJ known so far. That is, the As content (As/(Gα+A8)) of the crystal raw material melt is around 50 cm, the pressure during crystal pulling is 3 to 70 atm, and the heating temperature of the crucible is 12
Near 60°, the pulling speed of the seed crystal is 2 to 10 m 7
At the time, the present invention provides a crucible with Ga and A as crystal raw materials.
s and B as a sealant, 0. When filling the crucible, put in a predetermined amount of p-type impurities zn and In, load the crucible into a high-pressure container, and when the high pressure heats up and the raw materials in the crucible melt,
The crystal is pulled under the above conditions.

(Function) As mentioned above, when growing a p-type GaAs single crystal by the LEC method, if I′rL is made to coexist with Zn as a p-type impurity in the crystal raw material melt, zn will be uniformly distributed over the entire surface of the wafer. Dispersed crystals grow. The reason why the p-type impurity is uniformly dispersed in this way is that in the crystal substrate grown by adding In and ztL, the number of dislocations is greatly reduced compared to the conventional one, and there are no dislocations over the entire wafer surface. , the incorporation of zn due to dislocations is eliminated, and therefore the dispersion of zn becomes uniform. Note that no effect was observed due to the addition of xn.

Furthermore, GaA containing 2 and In according to the method of the present invention
$ When a single crystal substrate was etched using the molten KOH method and the etch bits were observed, approximately 10,000 bits were observed per 12 bits in the conventional p-type GaAs crystal substrate, but 0 to 1000 bits were observed in the crystal substrate according to the present invention. It has been revealed that high quality p-type GaAs single crystals can be obtained even if the number of crystals is small as /-.

If p-type impurities are uniformly dispersed in the crystal substrate formed in this way, the conductivity will be almost the same at any position, and if an optical device is formed using this as a substrate, an optical device with the same characteristics will be produced. This means that it can be obtained at a high rate and is highly reliable.

(Example) G was placed in a cylindrical PBN crucible with an inner diameter of 10 m and a height of 10 α.
A is 470fXA8 is 550f, In is 50? ,Zn
2t, B, O, 200? as a sealant? This PBN crucible was loaded into a high-pressure container, and the inside of the container was pressurized to 30 atmospheres with argon gas, and then the crucible was heated to 1265 ° C. with a heater provided so as to surround the crucible.
When the crucible has two layers of crystal raw material melt and sealant melt, lower the crystal pulling shaft installed at the top of the crucible, and pass the seed crystal attached to its tip through the sealant melt. The crystal was brought into contact with the crystal raw material melt, and then the crystal was pulled up at a speed of about 8 seconds without rotating the crystal pulling shaft.
A GaAs single crystal was obtained.

A wafer was cut out from this crystal and the contents of Zn and In were measured. As a result, Zn was about 1 x 10"/d and In was about 1 at both the center and the periphery of the wafer.
They were dispersed at a rate of X10' pieces/crd.

After polishing this cut wafer, 50 infrared semiconductor lasers were fabricated using it as a substrate, and the threshold current was measured, and it was found to be in a narrow range of 75'rrLA to 85'rrLA.

For comparison, a p-type Gaps single crystal wafer not containing In was cut out, a semiconductor laser was fabricated in the same manner as above, and the threshold current was measured.
? There was a very large variation of 7 tA.

In addition, when laser oscillation was performed under the conditions of 70°C and 5TrLW, the average oscillation time of the laser using the crystal of the present invention as the substrate was 650 hours, compared to that of the laser using the conventional crystal as the substrate. This was about twice the average oscillation time of about 180 hours. In addition, the laser yield was about 0.5 to 1.0 inches when a conventional crystal was used as a substrate, but the yield of a laser using the crystal according to the present invention as a substrate was about 2.5 inches. Improved.

(Effect of the invention) Until now, G
It has been difficult to produce APS single crystals, but according to the present invention, p-type fumugi and I? are added to the crystal raw material melt. By coexisting with +, a conductive GaA3 single crystal wafer in which p-type impurities are almost uniformly dispersed can be obtained. As a result, the growth rate of p-type Ga55 single crystal is fast, large-diameter circular wafers are obtained, and the quality is also improved, so that it can be used as a substrate for optical integrated circuits and optical devices to improve reliability. A high-quality product can be obtained, and the yield will be greatly improved, making a great contribution both economically and technologically.

[Brief explanation of the drawing]

The drawing is a table showing the relationship between the amounts of zn and Is added and the luminous efficiency when a diode was manufactured using the formed GaAs crystal as a substrate. J-Land stocks and shares (Omu) Procedures and formalities (method) April 1985 Ayuta

Claims (3)

[Claims] (1) In a method for producing a gallium arsenide single crystal by a liquid-sealed rotational pulling method in which a seed crystal is brought into contact with a crystal raw material melt and pulled up, a gallium arsenide melt containing p-type impurities and indium is used as the crystal raw material melt. A method for producing a p-type gallium arsenide single crystal, the method comprising pulling the crystal using a p-type gallium arsenide single crystal. (2) The method for producing a P-type gallium arsenide single crystal according to claim 1, wherein the p-type impurity is zinc. (3) The method for producing a p-type gallium arsenide single crystal according to claim 1 or 2, wherein the amount of indium added is in the range of 0.1 to 1000 times the number of p-type impurities added. .