JPH0735318B2 - <II>-<VI> Group compound single crystal growth boat - Google Patents

Description

TECHNICAL FIELD The present invention relates to a boat for growing a II-VI compound single crystal. More specifically, the present invention relates to a boat for growing a II-VI compound single crystal capable of preventing the loss of raw materials and improving the yield.

<Prior Art> Conventionally, various methods have been used as a method for producing a II-VI group compound single crystal. One of such methods is for growing a single crystal as shown in FIG. The horizontal Bridgman method using a boat can be mentioned. An example of producing a II-VI group compound single crystal, for example, a CdTe compound single crystal using this apparatus will be described. A reaction vessel (6) in which a reaction section (4) and a reservoir section (5) are connected by a capillary. After adding an appropriate amount of Cd to the reservoir part (5) and charging the CdTe compound raw material into the single crystal growth boat (7) provided in the reaction part (4), the reaction vessel (6) is depressurized. And make a vacuum. Then, when the reaction vessel (6) is externally heated by the furnace (8), the CdTe compound raw material gradually absorbs Cd, and finally becomes a melt (9) having a stoichiometric composition. A CdTe compound single crystal (seed crystal) held on a shelf provided at one end of the crystal growth boat (7) is brought into contact with the melt (9) to start crystal growth. After that, the temperature distribution of the furnace (8) is moved (the furnace or boat is moved depending on the device) to grow a crystal, and Cd
A Te compound single crystal (10) is produced. In the above-mentioned manufacturing method, the temperature distribution of the furnace (8) is such that the single crystal is grown while controlling the vapor pressure inside the reaction vessel (6).
Usually, as shown in FIG. 4, a stoichiometric range is set in a temperature range equal to or higher than T1 (melting point of CdTe compound), a temperature range of T2 which is a temperature between T1 and T3 described later, and a reaction system. In order to maintain the vapor pressure suitable for obtaining the compound, there are three constant temperature zones in the temperature region of T3 which is the heating temperature required for vaporizing the vapor pressure control substance (Cd in the above example).

Cd that dissociates from the melt (9) and tries to escape
The composition of the melt (9) is prevented from changing by controlling the vapor pressure and the vapor pressure of Cd in the reservoir (5) to be equal.

<Problems to be Solved by the Invention> However, CdTe compounds have a large dissociation pressure at the melting point, and both Cd and Te show high vapor pressures. In particular, since Cd has a high vapor pressure, even when the Cd pressure is controlled by stoichiometric composition as in the above method, the surface of the melt (9) in the single crystal growth boat (7) flows into the reservoir section (5). Evaporation occurs,
There is a problem that the loss of raw materials is large. At this time, evaporation of Cd from the melt (9) is suppressed by the vapor pressure control described above, but cannot be controlled when both vapor pressures of Cd and Te are high. In particular, when a large single crystal is manufactured, the growth boat also becomes large and the surface area becomes large, so that the loss due to evaporation becomes large.

<Object> The present invention has been made in view of the above problems, and provides a boat for growing II-VI compound single crystals capable of controlling evaporation from the surface of the boat for growth and preventing loss of raw materials. To aim.

<Structure> II-VI of the present invention made to achieve the above object
The group compound single crystal growth boat is characterized by being a capped single crystal growth boat having an opening, and the opening preferably has a small area.

<Operation> The present invention has the above-described configuration, and since the melt in the growth boat is covered with the lid having the opening, the lid serves as a resistance against evaporation from the surface of the melt, thereby reducing the loss of the raw material. Can be reduced. In particular, if the opening has a small area, this effect becomes even greater.

Here, the reason why the opening is provided is as follows.
For example, in the horizontal Bridgman method for producing a CdTe compound single crystal, as described above, Cd placed outside the boat inside the reaction vessel
Is heated to gradually absorb the Cd vapor into the melt in the boat, and finally form a CdTe melt having a stoichiometric composition. Therefore, the opening functions as an entrance for Cd vapor.

<Example> Hereinafter, a detailed description will be given based on the accompanying drawings showing an example.

FIG. 1 is a perspective view showing an embodiment of a boat for growing a II-VI group compound single crystal according to the present invention, which comprises a boat bottom portion (1), a lid (2) and an opening portion (3). The bottom part (1) of the boat is substantially the same as the conventional single crystal growth boat. The upper opening surface of the boat bottom (1) is covered with a lid (2), and the lid (2) is provided with a slit-shaped opening (3) along the width direction of the lid (2). The boat bottom (1) and the lid (2) may be sealed by fusion or the like, but the effects of the present invention can be sufficiently achieved without sealing. The shape of the opening (3) is
The shape is not particularly limited, and may be a slit shape as described above, a small hole shape, or the like. Also, divide the lid (2) into two,
The opening (3) may be formed by covering the divided bottom (2) on the boat bottom (1) at a small interval. Further, the opening (3) may be provided along the length direction of the lid (2), unlike the above embodiment.

In the present invention, the area is more important than the shape of the opening (3), and the area of the opening (3) is 10 mm ²
The following is preferable from the viewpoint of controllability.

As the material of the boat bottom (1) and the lid (2),
Transparent quartz is preferable from the viewpoint of observing the crystal growth state from the outside, but when observation is unnecessary so that the production is carried out under preset conditions, ceramics, BN, SiC, Al ₂ O ₃ etc. Good.

Next, an example of the method of using the single crystal growth boat according to the present invention will be described. First, inside the boat bottom portion (1) II-
After filling the group VI compound single crystal raw material and covering it with a lid (2) having an opening (3), it was placed at a predetermined position of the reaction section (4) of the apparatus shown in FIG. ) Is depressurized to vacuum. Hereafter, according to the conventional horizontal Bridgman method,
A II-VI compound single crystal is grown. In the above manufacturing method, it is preferable to provide the opening (3) on the rear side in the crystal growth direction in order to control the vapor pressure. Therefore,
Also when providing the opening (3) in the lid (2), it is preferable to provide the opening (3) at a portion near one end in the length direction of the lid (2).

Hereinafter, the present invention will be described in more detail with reference to experimental examples.

Experimental Example A single crystal growth boat (length 170 mm, width 20 mm, depth 10 mm) shown in FIG. 1 having different slit areas was prepared, and after a certain amount of a CdTe compound raw material was charged in the boat,
Installed at the specified position of the reaction part of the device shown in FIG.
It was heated under the temperature conditions of = 1170 ° C, T2-1050 ° C and T3 = 820 ° C, and the loss amount of the raw material was measured. The amount of loss is measured by CdTe
It was determined by the difference in weight of the boat containing the compound before and after heating. The results are shown in FIG.

As is clear from FIG. 2, the loss amount increases in proportion to the opening area up to a certain opening area (S0), but when it exceeds S0, the loss amount does not change, and the Cd partial pressure and the melt temperature The impact will be stronger. Results of various experiments, critical points
S0 slightly changes depending on the Cd partial pressure and the melt conditions, but exists in the range of approximately ² to 10 mm ² . Therefore, the area of the opening is preferably 10 mm ² or less.

<Effect> As described above, according to the boat for growing II-VI compound single crystal of the present invention, the lid having the opening suppresses evaporation from the melt surface, so that loss of raw material can be prevented and production It has a unique effect that it can contribute to the improvement of sex.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a boat for growing a II-VI group compound single crystal according to the present invention, FIG. 2 is a view showing a relationship between an opening area and a loss amount in an experimental example, FIG. FIG. 4 and FIG. 4 are a schematic diagram of an apparatus used in the horizontal Bridgman method and a schematic diagram of an example of temperature control, respectively. (1) …… bottom of boat, (2) …… cover (3) …… opening

Front Page Continuation (72) Inventor Kenji Miyazaki 1-3-3 Shimaya, Konohana-ku, Osaka City, Osaka Prefecture Sumitomo Electric Industries, Ltd. (56) Reference JP-A-59-83914 (JP, A) Showa 57-47795 (JP, A) Actually opened Showa 58-129634 (JP, U)

Claims (2)

[Claims] 1. A boat for growing a single crystal used for producing a II-VI compound single crystal by the horizontal Bridgman method, wherein the boat is a covered boat having an opening. Compound single crystal growth boat. 2. The boat for growing a II-VI group compound single crystal according to claim 1, wherein the area of the opening is 10 mm ² or less.