JPS62105999A - Method for producing gaas single crystal and apparatus used therefor - Google Patents

Abstract

PURPOSE:To facilitate the growth of an impurity-doped GaAs single crystal having excellent crystallinity, by separately placing an impurity from Ga and As used as raw materials and from a seed crystal, contacting the raw material with the impurity in the course of heating and product. CONSTITUTION:An As source 4 used as a raw material is placed at an end in a quartz tube 1 and quartz boat 3 containing another raw material Ga 12 is placed at the other end of the tube 1. A seed crystal 5 is placed on a step formed at an end of the boat 3 and an impurity 11 such as Si is placed on another step formed at the other end of the boat and having lower height than the former step. The quartz tube 1 is evacuated, sealed and heated in a furnace 20. The evaporated As source 4 is made to react with molten Gas 12 and the impurity 11 and, at the same time, oxides existing in the components are evaporated. The boat 3 is inclined to introduce and mix the impurity 11 in the form of SiAs, etc., into the molten GaAs in the boat 3. The molten liquid is brought into contact with the seed crystal 5 by tilting the boat to the opposite side to effect the growth of a GaAs single crystal doped with a specific amount of an impurity such as Si.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sawing method for producing GaAs single crystals and an apparatus used therefor.

[Summary of the Invention] The present invention provides impurity-doped GaA: 1 antagonist crystals, which are the main components of the crystals.
': Place the blunt object in such a way that it does not come in contact with it, and make sure that Ga and impurities come into contact with each other during the temperature raising process during crystal growth. Avoid ignition.

[Conventional technology]

Ii of n-d with 1-bubble Si impurity, 1 crystal of IAs! Methods for this include the 1113 method (horizontal Alitzman method) 5 or the GF method (G: igent freeze 7'J:). And 11 of this kind
GaAs is widely used in various compounds 1 (conductors, such as semiconductor lasers, light emitting diodes, semiconductors in field effect transistors) (treatments 1 and j).

GaAs doped with such impurities, e.g. Si
There are two methods for growing single crystals, depending on the person.

The first method is to add Si to Ga and add this to As.
This is a method of growing a single crystal by reacting with

To explain this with reference to Figure 2, in this case,
Ga in the reaction (hereinafter referred to as quartz tube) (1) made of quartz
Quartz boat (3) containing raw material (2) with Si added to
) and place As in the quartz tube (1) at a different position.
Place the source (4). On the other hand, a GaAs seed crystal is placed on the edge of the boat (3) at a distance from the raw material (2).
The boat (3) is tilted to bring the raw material melt (2) into contact with the seed crystal (5) to grow a single crystal from the seed crystal (5). However, in this method, Ga2e and Ga2O3 present in Ga
oxides such as oxides easily react with Si to produce reaction products such as 5i(h (solid) and SiO (gas), which may contaminate the quartz boat (3) or the melt of the raw material (2). This may cause fluctuations in the composition inside, making it impossible to accurately produce the desired amount of Sif.
Alternatively, the adhesion of the reaction products described above becomes abnormal growth seeds, which inhibits the growth of single crystals and causes problems such as generation of twins or polycrystals. Therefore, when such a method is adopted, Ga oxides and As oxides are removed by baking in vacuum or in a reducing gas at a temperature lower than the temperature during crystal growth. After that, a method is adopted in which a single crystal is grown while carrying out an As reaction under high-temperature heating.However, such work is extremely complicated and hinders mass production.

In addition, the second method uses the boat [:i
4) A raw material (2) prepared in advance as a polycrystalline material in which Si is added to undoped or Si-doped Ga is stored, and this is remelted to grow a single crystal in the same manner as in the first method described above. It is something to do. However, this method requires the labor and equipment to prepare the polycrystalline body in advance, resulting in high costs.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems and enables simple work.
The present invention provides a method for producing a GaAs single crystal and an apparatus for use in the method, in which the 5iiJ degree of crystallinity can be accurately set.

[Lower section for solving problems]

The present invention, as in the 1111 method, Gf' method, etc.
In a method for manufacturing a compound semiconductor single crystal using Ga and ΔS as raw materials and adding impurities to them, Ga, ΔS, and an impurity such as Si are separated, and 3 The method is to bring it into contact with someone and then crystallize it.

The present invention also relates to an apparatus for carrying out this method, and as shown in FIG.
) is set apart from the Ga (12) installation location in the boat (3) and the seed crystal.

Then, the impurity (11) is set at a position below, that is, lower than the seed crystal (5) in the direction of gravity.

Further, Ga is set at a lower position than the set position of the impurity (11).

In this way, first, prior to growing a GaAs single crystal, the Ga and ΔS sources previously stored in a boat are each hakened in a state where they are supplemented by 1/2, and then evacuated to remove oxides.
Seal the quartz tube (1). Next, ^S from the As source (4) is heated and evaporated at a lower temperature than the portion in the port 13). In this way, as the temperature rises 7, this ^S
The steam is transported into the Ga of the boat (3), and the Ga
Generation of As begins. At the same time, the remaining oxides of Ga are generated in the form of Ga20a + Ga2O, which becomes an As source (
4), that is, the part outside the boat (3) that is not involved in single crystal growth. At the same time, As is transported to the impurity Si and reacts with the Si to form a liquid of 5iAs. At this time, the temperature of the portion where the impurity 5i (11) is placed is:
The temperature is selected to be sufficiently higher than the temperature at which the Ga oxide is precipitated.

The 5iAs liquid produced in this way is allowed to flow into the hoard (3) by tilting the furnace as necessary, so that Ga, GaAs, and 5iAs are formed in the boat (3).
A mixed melt with s is produced.

Next, the melt in the boat (3) is raised by raising its liquid level.
Alternatively, the seed crystal (5) may be brought into contact with the seed crystal (5) by shortening the furnace as necessary, and the heating temperature and temperature distribution may be adjusted as needed.
Then, grow the single crystal as usual.

[Effect]

As described above, in the present invention, Ga, As, and impurities such as Si are separated in advance, and Ga or Ga(!:G
Crystal growth is performed after Ga oxide is scattered from the melt with aAs, but at this time, as mentioned above, the location of the impurity Si is set at a temperature sufficiently higher than the precipitation temperature of the Ga oxide. This prevents Ga oxide from being mixed in. In reality, the evaporation and scattering of Ga oxide is reported as Ga2O gas by ΔS.
By reacting with Ga oxide to form gases such as As2O and AS203, Ga oxide is effectively removed from the crystal growth zone, making it possible to produce a single crystal with excellent crystallinity with a stable Si doping amount. You can grow up, do things, and become two.

〔Example〕

An embodiment of the present invention will be explained in A11 with reference to FIG.

For example, AJf4) is placed at one end of the quartz tube (1), and a quartz boat (3) is placed at the other end. Quartz boat (
3), on opposite sides of their upper edges, (IjII, for example, this board 1-t3131 internal steps are provided, and the seed crystal (5) is placed on one side, and the impurity (Ill, in this example, Sl) is placed on the other side.
Place 1. Bow 1- (31 is Ga(12)
to accommodate.

At this time, impurity 5i (11) is 7
teAsf)i! f4) is placed on the opposite side. and,
Heat the area where the As source (4) is placed to 250°C, and place it in the hoard (
3) Heat the Ga inside to 600°C. At this time, the inside of the quartz tube (1+ is exhausted to lO''''~10'''1'+n fli!, and the Ga oxide Ga2O is exhausted to the outside of the tube. At this time, Sμm1 body and Ga2O gas There was almost no reaction with Sin, 5i02.
No formation was observed. Next, the quartz tube 10 is vacuum-sealed as shown to the first foreigner, and a heating furnace (2
0) Install inside. At this time, a small amount of Ga oxide (13) still remains in Ga (12).

In this state, the temperature of the Kataha furnace (20) is increased and As
Ga (12
) is raised to 900 to 1000°C, as schematically shown by arrow a in Figure 1 F3, 1s is emitted once as the temperature of the furnace is t, and the Ga in the hoard (3) is Transport of As occurs, and the quaternary formation of GaAs begins in Ga, resulting in the formation of GaAs in Ga.
The melt containing aAs becomes IJ(). -The remaining Ga oxide (13) is G, +201, Ga2O
As shown schematically by the arrow, it precipitates on the lower side, specifically, for example, on the side where the As source (4) is placed, and at least from the boat (3) involved in the formation of the As crystal. That is, it is excluded from the vicinity of the single crystal growth part of the seed crystal (5) and from the GaA solution containing G rr As.

At the same time, As is schematically shown by arrow C, the Si impurity (II) is also transported, and a liquid of 5iAs begins to be formed at a temperature of about 786° C. or higher. At this time, S
Since the temperature of the i-specific generation site, that is, the location of impurity (11), is much higher than the Gol oxide precipitation temperature, 5iA
The reaction between s and Gil oxide is difficult to occur, and even if it does occur, it will take the form of As20 or As20a, and since the stem pressure is high, the reaction will occur on the other side, that is, on the side where the As source (4) is arranged. oxidation of 5iAs hardly occurs. Then, the 5iAs(7) liquid produced in this way is poured into a boat (3) by tilting the furnace as necessary.
) As shown in FIG. 1C, a mixture of Ga, GaAs, and 5iAs (Wb?) is introduced into the boat (3) by flowing the inner layer. fl.

Make (1, 4) raw.

Next, the melt (14) in the boat (3) is brought into contact with the seed crystal (5) by means of its surface blades, or similarly by blowing the furnace (', A single crystal is grown in the usual manner with a required heating gain of 1 and a temperature distribution of Qζ31.

In the example shown in the figure, the boat (3) itself has a part for placing the seed crystal (5) and a part for placing the impurity 5i (11). Seed crystal (5) and impurity 5i (
11) Arrange 2 t: Make a structure for hanging the hanger.

In addition, in the example described in Section 5, an n-type GaAs single crystal is grown with impurities of 1 m (11) or Si, but GaAs doped with other n-type impurities or p-
The present invention can also be applied when using a type impurity such as Zn.

〔Effect of the invention〕

As described above, according to the present invention, the Ga oxide is effectively eliminated, so that the impurity doping concentration can be accurately set to achieve excellent crystallinity, which drastically reduces the occurrence of crystal defects such as the occurrence of twins. It is possible to produce GaAs single crystals with a small amount of work, and its industrial advantages are extremely large.

[Brief explanation of drawings]

FIGS. 1A to 1C are manufacturing process diagrams of an example of implementing the manufacturing method of the present invention using the apparatus of the present invention, and FIGS. 2 and 3 are explanatory diagrams of the conventional method. ill is a reactor core tube (quartz tube), (3) is a boat, (4) is an As source, (5) is a seed crystal, and (11) is an impurity. Figure 1

Claims (1)

[Claims] 1. In a method for producing a GaAs single crystal using Ga and As as raw materials and adding impurities to the raw materials, after the Ga and As are brought into contact with the impurities during the temperature raising process during crystal growth. A method for producing a compound semiconductor single crystal by crystallization. 2. In an apparatus used in a method for producing a GaAs single crystal using Ga and As as raw materials and adding impurities thereto,
A device for producing a GaAs single crystal, in which the impurity installation location is separated from the Ga installation location and the seed crystal. 3. In an apparatus used in a method for producing a GaAs single crystal using Ga and As as raw materials and adding impurities thereto,
Separate the seed crystal installation part and impurity installation part of the boat where Ga is installed, and the Ga installation part and impurity installation part, and make the impurity installation part the same or lower than the seed crystal installation part with respect to Ga. A device for producing GaAs single crystals.