JPS5813487B2 - Kagobutsuno Gouseisouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides
The present invention relates to a synthesis apparatus using a sealed tube for -■ group compounds, particularly GaAsP compounds.

The present inventors have been working for some time to develop a technology for synthesizing ■-■ group compounds containing at least two or more types of group V elements, and the results were first published in Japanese Patent Application No. 48-63631. It was proposed as Publication No. 50-10796.

The gist of the invention of Japanese Patent Application No. 48-63631 is that [a synthesis method using a sealed tube of a ■-V group compound containing at least two or more types of group ■ elements,
The type is introduced through a differential pressure valve into a sealed tube containing a heated group III element, and this and other group III elements previously sealed in the sealed tube are simultaneously absorbed into the group III element to create a uniform composition. 1. A method for synthesizing a compound, which comprises synthesizing a group IV compound containing multiple components.

'', which made it possible to synthesize a compound with a homogeneous composition by creating the technical idea of using a differential pressure valve.

It goes without saying that the differential pressure valve necessary for carrying out the invention of Japanese Patent Application No. 48-63631 need not be limited to a particular structure as long as it satisfies its function.

The inventors also tried various known differential pressure valves and obtained reasonable results with each.

However, from the perspective of impurities incorporated into the synthesized compound,
It is safe to say that there is no perfect differential pressure valve from many points of view, including operability and the structure of the synthesizer.

The differential pressure valves that gave relatively satisfactory results were either orifices made by drilling holes in quartz plates, or they were inadequate from the viewpoint of easily controlling minute differential pressures.

An object of the present invention is to provide a compound synthesis apparatus suitable for synthesizing compounds consisting of Ga, As, and P.

The basic configuration of the synthesis apparatus according to the present invention is as illustrated in FIG. 1a.

Although the vertical arrangement of FIG. 1a is reversed from that of the example of the synthesis apparatus shown in FIG. 3a of Japanese Patent Application No. 48-63631, there is no essential difference between them. do not have.

Now, from the top, the synthesis apparatus illustrated in FIG.
It is arranged and configured with a chamber for accommodating other group Ⅰ elements.

In order to make the explanation clear, the following will explain in detail the case where gallium phosphide arsenide is synthesized using gallium as the group ■ element 1, metallic arsenic as the group ■ element 2, and red phosphorus as the group V element 3. do.

Once the group ■ elements and group V elements to be used are identified in this way, the set temperature of the chamber containing each element is determined.
In this case, a temperature distribution as shown in FIG. 1b shown side by side with FIG. 1a is exemplified.

Now, the feature of the synthesis apparatus according to the present invention lies in the configuration of the differential pressure valve.

The present inventors used a quartz capillary tube instead of the hole in order to improve the drawbacks of the orifice in which a hole was made in the quartz plate,
We considered controlling the conductance of the differential pressure valve by changing the shape, inner diameter, and length of the quartz capillary.

That is, it has a configuration as shown in the longitudinal section in FIG. 2, and consists of a quartz capillary tube 6 sealed to a quartz plate 5.

7 shows the situation when metal arsenic is housed in a synthesis apparatus, and corresponds to 2 in FIG. 1a.

By using a synthesis apparatus having the configuration shown in FIG. 1a and equipped with the differential pressure valve shown in FIG. 2, it was possible to obtain gallium arsenide phosphide crystals having a uniform composition.

In this case, the quartz capillary tube 6 sealed to the quartz plate 5 allows phosphorus vapor to be introduced into the gallium and metal arsenic storage chamber, but serves to prevent the arsenic vapor from dispersing into the red phosphorus storage chamber. It is something.

This is because the vapor pressure of red phosphorus is higher than that of arsenic.

However, as a result of continuing experiments using a differential pressure valve and a quartz capillary tube 6 (Fig. 2) sealed to a quartz plate 5, it was found that if the diameter of the quartz capillary tube was 0.2 mm or less and the length was 50 mm or more, crystallization occurred. Most of the composition was uniform, but it was found that the concentration of gallium phosphide decreased at the tip of the ingot of the synthesized compound (Figure 5-a).

This was because the quartz capillary was too thin and it took a long time for the phosphorus vapor to flow into the gallium storage chamber, causing gallium arsenide phosphide crystals to grow before the phosphorus vapor and arsenic vapor reached equilibrium. .

In addition, in an example using a quartz capillary tube with a larger diameter, the compositional non-uniformity at the tip of the ingot was greatly improved, but the concentration of gallium phosphide increased at the rear end of the ingot. I understand (Figure 5-b).

This was because the quartz capillary was too thick, allowing arsenic vapor to diffuse into the red phosphorus storage chamber, lowering the arsenic vapor pressure.

In contrast, by providing a synthesis apparatus according to the present invention, the problem of compositional non-uniformity occurring at the leading or trailing end of a grown crystal can be solved and a compound having a uniform composition throughout the ingot can be synthesized. It is possible to provide a device for

According to the present invention, there is obtained a synthesis apparatus equipped with a differential pressure valve consisting of a quartz capillary tube and a liquid metal seal, which is used when synthesizing a compound in a vertical closed reaction vessel.

The quartz capillary acts as a fine pressure regulator and the liquid metal seal acts as an overpressure regulator to obtain a uniform composition throughout the ingot.

FIG. 3 shows a cross-sectional view of an improved differential pressure valve according to the invention.

8 is a quartz capillary tube, 9 is a liquid metal, 10 is a liquid metal holding plate, 11 is an overpressure adjustment hole, 12 is a metal arsenic holding plate, 13
is metallic arsenic.

Next, the function of this differential pressure valve will be explained.

First, a predetermined amount of gallium, metallic arsenic, and red phosphorus are sealed at predetermined positions in a closed reaction vessel, and indium or gallium is used as a liquid metal seal.

Next, the inside of the sealed reaction vessel is evacuated, and the vessel is placed in an electric furnace and the temperature is raised.

The melting points of indium and gallium used as liquid metal seals are 156°C and 29.7°C, respectively, so if the temperature at the differential pressure valve is at least 160°C, indium and gallium will work as liquid metal seals. Become.

For example, if the temperature of red phosphorus is 420°C, the vapor pressure of phosphorus is 1 atm, and if the temperature of metal arsenic is 550°C, the vapor pressure of arsenic is 0.3 atm, so at the differential pressure valve it is 0.7 atm. An excessive pressure difference initially exists.

This excessive pressure difference pushes down the liquid metal 9 in the overpressure adjustment hole of FIG. 3, and finally the seal breaks and phosphorous vapor flows into the metal arsenic storage chamber.

This inflow of phosphorus vapor continues until the pressure difference at the differential pressure valve is almost eliminated.

That is, 0.7 atm of phosphorous vapor flows into the metal arsenic storage chamber.

As a result, the vapor pressure of phosphorus on the red phosphorus storage chamber side is 1 atm, and on the metal arsenic storage chamber side, the arsenic vapor at 0.3 atm and the phosphorus vapor at 0.7 atm become 1 atm, and the pressure at the top and bottom of the differential pressure valve becomes 1 atm. balance.

Then, the inside of the overpressure adjustment hole 11 is again filled with the liquid metal 9 and sealed.

After this point, even if crystals grow, there will be no large pressure difference between the top and bottom of the differential pressure valve, so the liquid metal seal will not break.

That is, as the gallium arsenide phosphide crystal grows, the metal arsenic and phosphorus vapor in the gallium storage chamber are consumed, and the phosphorus vapor tends to decrease little by little, but the reduction is very slow, so Such a minute pressure decrease is compensated for through the quartz capillary tube 8 for minute pressure adjustment, and the pressure is balanced above and below the differential pressure valve, and the partial pressures of phosphorus and arsenic vapor in the metal arsenic and gallium storage chamber are kept constant. As a result, a gallium arsenide phosphide crystal having a uniform composition throughout the ingot as shown in FIG. 5-C can be obtained.

In addition, since the diameter of the quartz capillary can be made sufficiently thin, the diffusion of arsenic vapor into the red phosphorus storage chamber is negligible.
A small quantity of metallic arsenic alone will not increase the concentration of gallium phosphide at the rear end of the ingot, as shown in FIG. 5b.

FIG. 4 shows another embodiment having a similar effect, in which 14 is a quartz capillary, 15 is a liquid metal, 16 is an overpressure adjustment hole, and 1
7 is metal arsenic, 18 is a liquid metal reservoir, and 19 is an arsenic crucible with a differential pressure valve.

That is, this device can contain red phosphorus and metallic arsenic at the same time, and also functions as a differential pressure valve similar to the device shown in FIG.

In the device shown in FIG. 3, the encapsulation of red phosphorus and the encapsulation of metal arsenic and gallium must be performed separately, but in the device shown in FIG. 4, red phosphorus, metal arsenic, and gallium can be encapsulated at the same time.

That is, the arsenic crucible with a differential pressure valve shown in FIG.
8, put the red phosphorus in the specified position, then put metal arsenic and a liquid metal for sealing into the arsenic crucible with a differential pressure valve, and then put the arsenic crucible with the differential pressure valve into the liquid metal reservoir 18.
Just put it inside.

Since the liquid metal in the liquid metal reservoir is much larger in quantity than the liquid metal 15 for regulating overpressure, it does not act as a pressure regulating valve, but only as a seal.

Two examples have been described above, but there are various other variations of differential pressure valves that use quartz capillary tubes for fine pressure adjustment and liquid metal seals for overpressure adjustment, but all of them are based on the original principle. It is clear that this can be considered based on the invention.

[Brief explanation of the drawing]

FIG. 1 shows an outline of the apparatus used for synthesizing a compound having a uniform composition, in which a shows a cross section of the apparatus and b shows the temperature distribution within the apparatus. Figure 2 shows a conventional differential pressure valve consisting of a quartz capillary tube;
The figure shows an improved differential pressure valve consisting of a quartz capillary and a liquid metal seal according to the invention, FIG. 4 shows one modified differential pressure valve according to the invention, and FIG. 5 shows the composition of the crystals obtained. Fig. 2 is a diagram showing changes in the growth direction of , where a and b are obtained by the method shown in Fig. 2, and C is obtained by the present invention. 1...Gallium, 2...Metal arsenic, 3...Red phosphorus, 4...
Differential pressure valve, 5...Quartz plate, 6...Quartz capillary, 7...Metal arsenic, 8...Quartz capillary, 9...Liquid metal, 10...Liquid metal holding plate, 11...Excess pressure adjustment hole, 12 ...Metal arsenic holding plate, 13...Metal arsenic, 14...Quartz capillary,
15...liquid metal, 16...excess pressure adjustment hole, 17...
Arsenic, 18...Liquid metal reservoir, 19...Arsenic crucible with differential pressure valve.

Claims (1)

[Claims] 1. In a compound synthesis apparatus using a vertical sealed tube comprising a chamber for containing potassium, a chamber for containing arsenic, and a chamber for containing phosphorus, the chamber for containing arsenic and the chamber for containing phosphorus. and an arsenic holding plate provided with a quartz capillary tube are separated by a differential pressure valve formed by placing an arsenic holding plate in a liquid metal held on a liquid metal holding plate.