JPS5912638B2 - Direct synthesis method for intermetallic compounds containing volatile components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the use of a compound containing a volatile component as one of its components, for example, m-
The present invention relates to a method for directly synthesizing intermetallic compounds such as V group, II-Vl group, Vl-Vl group, etc.

These intermetallic compounds usually do not occur naturally, so in order to obtain industrially valuable single crystals, it is first necessary to synthesize these compounds.

Conventionally, among these compounds, GaAs and GaP, which have been in the spotlight in recent years, have high melting points, and their constituents, As and P, exhibit vapor pressures that increase exponentially with increasing temperature. Although it was thought that it would be impossible to synthesize the volatile components, in Japanese Patent Publication No. 52-33041 (Japanese Patent Application No. 12538-1982), the inventors blended an excessive amount of volatile components and changed the atmosphere of the reaction system to remove the volatile components. It was revealed that the above compounds can be directly synthesized without using a sealed tube if the atmosphere is a high-pressure inert gas atmosphere higher than the vapor pressure of the chemical component and the heating reaction time is short. did.

After that, it was about to be delayed from this invention - in the afternoon JP-A-47
As disclosed in No.-556, B2 is further added to the above invention.
A method of directly synthesizing the above compound by adding a liquid coating material such as O3 was proposed.

However, even if this latter method is used, it is still not possible to prevent volatile components from forming bubbles and evaporating inside the liquid coating material during synthesis, which is why the present invention was made.

Therefore, the object of the present invention is to further prevent the evaporation of volatile components outside the reaction system than those of the prior art.
It is an object of the present invention to provide a method for directly synthesizing the above-mentioned intermetallic compounds.

The present invention will be explained in detail below based on the drawings. In FIG. 1, 1 is a heating element consisting of a resistance heating element or a high-frequency heating coil, etc.; 2 is a crucible support that is moved up and down by a device not shown; 3 is a crucible, 3a is its upper cover, 3b is a gap created between the upper cover 3a and the crucible 3,
4 is a composition melt of a target compound such as GaAs or GaP, 5 is a liquid coating material such as B2O3, and an inner lid 6 is suspended between the liquid coating material 5 and the composition melt 4. There is.

According to the embodiment, high-purity gallium and high-purity arsenic, an inner lid 6 made of quartz having an outer diameter slightly smaller than the inner diameter of the crucible 3, and a solid disc-shaped B2O3 that fits the crucible 3 are used.
After the crucible 3 containing the crucible was placed on the support stand 2, the inside of the furnace (not shown) was evacuated and argon inert gas of about 100 atmospheres was introduced.

Then, the inside of the crucible 3 was also evacuated and pressurized through the gap 3b, and the internal and external pressures of the crucible 3 became equal.

Thereafter, the crucible 3 was moved inside the heating element 1 and heating of the expropriated material was started.

Then, the melting point of gallium is 29.8°C, the melting point of 2B2O3 is about 450°C, and the melting point of arsenic is 812°C, so as the temperature rises, the contents in the crucible will change to gallium, B2O3, and arsenic.
2O3 and arsenic are melted in this order, and the specific gravity of each is arsenic 5.73, gallium arsenide 5.3, quartz 2.6, and B.
2031.8, the melted contents were separated and stacked in the order of arsenic alone, gallium alone, inner lid 6, and B2O33.
The reaction system between arsenic and gallium was completely sealed,
Subsequently, the temperature inside crucible 3 was raised to about 1300°C.

Then, after 20 minutes have passed from the start of heating, heating element 1
The power was turned off, and the crucible 3 was lowered and allowed to cool.

The ingot thus obtained was found to be polycrystalline with a stoichiometric composition or an excess of arsenic as a result of microscopic examination.

FIGS. 2 and 3 show another embodiment, in which an inner lid 7 suspended within the crucible 3 is provided with concentric holes 7a.

When carried out in this manner, there is an advantage that the synthesis of the compound is followed by the pulling of the single crystal, and during this process the evaporation of volatile components can be prevented as much as possible.

According to the example, a total of 9509 pieces of high-purity arsenic and gallium and 709 pieces of B2 were placed in the quartz crucible 3 with an inner diameter of 70 yn.
O3 and an inner lid 7 made of quartz with a hole 7a of 30 mm slightly smaller than the outer diameter of 70 ynw were charged and heated under the same pressure and heating conditions as in the embodiment shown in FIG. Heated.

The reaction system was then completely sealed for the same reason as explained earlier.

After about 25 minutes have elapsed from the start of heating, the seed crystal 9 attached to the tip of the single crystal pulling rod 8 is passed through the B2O3 liquid coating material 5, penetrated through the hole 7a, and allowed to hang down.
After being immersed in the GaAs composition melt, the crucible 3 was heated to 6 r
, p, m, and the seed crystal 9 was pulled at a rate of 1211 LrIL/hour while rotating the seed crystal 9 in the opposite directions at approximately 12r, p, and m.

Then, the inner lid 7 lowers each time the liquid level drops, and most of the volatile components that try to evaporate out of the reaction system are blocked by the inner lid 7, so the evaporation prevention effect is extremely significant. Ta.

That is, when this inner lid 7 was not used, there was a evaporation loss of 2 g of arsenic under the same conditions as described above, but by using this, it was possible to suppress the loss to less than half.

Moreover, when the inner lid 7 was not used, 100 g of B2O3 was required, but when this was used, it was found that even 709 could sufficiently achieve the purpose.

The outer diameter of the obtained single crystal was 30 mm, which corresponds to the inner diameter of the hole 7a.

In the above embodiments, only the case where GaAs is directly synthesized was described, but this invention is applicable to GaAs other than gallium arsenide.
It is clear that this method can be applied to the production of intermetallic compounds containing volatile components such as.

In addition, other materials used for the inner lid include graphite, alumina, and B.
eO, B4C3, etc. should be appropriately selected depending on the type of the intended metal compound.

As explained in detail above, in this invention, since the inner lid further prevents the evaporation of volatile components, there is no need to mix excessive volatile components, and furthermore, it is possible to prevent the volatile components from evaporating by using the inner lid. In addition to saving on coating material, if you use a lid with a hole for pulling a single crystal, you can pull the single crystal immediately after synthesizing the target intermetallic compound. can be played.

[Brief explanation of drawings]

FIG. 1 is a schematic partial cross-sectional view of an apparatus for explaining the present invention, and FIGS. 2 and 3 are schematic partial cross-sectional views showing other embodiments. 1... Heating element, 2... Crucible support,
3... Crucible, 4... Composition melt, 5...
...Liquid coating material, 6゜7...Inner lid, 7a
······hole.

Claims (1)

[Claims] 1 Composition of an intermetallic compound containing volatile components When synthesizing a melt by the liquid capsule method, an inner lid is placed in a crucible containing an elemental component to be reacted and a coating material, and the elemental component is reacted with the elemental component. During this heating process, the reaction system is kept under pressure at a gas pressure higher than the vapor pressure of the reaction components, and through this heating reaction process, the liquid coating material and the compound crystals are heated. 1. A method for directly synthesizing an intermetallic compound containing a volatile component, the method comprising a step of suspending the inner lid between the composition and the melt.