JPH04295100A - Production of single crystal - Google Patents

Abstract

PURPOSE:To offer the method for massproduction of high-quality single crystals of semimagnetic semiconductors (Cd1-xMnxSe, Cd1-xMnxTe) and II-VI compd. semiconductors such as CdTe, etc. CONSTITUTION:In the production process of II-VI compd. semiconductor single crystals such as semimagnetic semiconductors (Cd1-xMnxSe, Cd1-xMnxTe), etc., a single crystal rod is first formed by Bridgman method. Their the rod is subjected to hydrostatic pressing at temp. higher than the phase transformation temp. of the material which constitutes this single crystal rod, in order to remove twin crystal.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a high-quality (twin-free) semimagnetic semiconductor (Cd1-X MnX
Te, Cd1-X MnX Se) and CdTe, Z
The present invention relates to a method of manufacturing a II-VI group compound semiconductor single crystal such as nSe.

0002

2. Description of the Related Art Conventionally, this type of single crystal has been produced by the following two methods. One uses a manufacturing apparatus schematically shown in FIG. 4(a). Cd1-X Mn
A method for producing single crystals such as X Te and Cd1-X MnX Se, in particular, the case of growing a single crystal of Cd0.5 Mn0.5 Te will be described. Crystal raw materials (for example, Cd, Mn, Te) are sealed in a transparent quartz tube ampoule according to the composition ratio under vacuum (degree of vacuum ≦1×10 −5 Torr) to form a quartz crucible 53 . A crystal raw material 56 that has been vacuum-sealed in advance in a quartz crucible 53 is heated using the temperature distribution shown in FIG. 4(b) in an electric furnace 51 such as a Bridgman furnace (
melting point, approximately 1050℃), and then placed in a quartz crucible 53
is lowered at a speed of 3 to 7 (mm/hr) using a crucible lifting mechanism placed above the electric furnace 51 to cause crystal growth to occur sequentially from the lower end of the quartz crucible 53, and then slowly cooled. A single crystal 55 is obtained. The single crystal obtained has a melting point (
= about 1050°C) to the phase transformation point (= about 850°C), it has a wurtzite type structure, and at temperatures below the phase transformation point (= about 850°C), it has a zincite type structure. Furthermore, Figure 4(b)
In the figure, H indicates the temperature range in which the crystal can be melted. When this manufacturing method is adopted, a phase transformation point is always passed during the crystal growth process. As for the cause of twinning, there is no problem if the entire structure transitions to the zincite structure when passing through the phase transformation point, but it is thought that points where the wurtzite structure remains partially become twinning.
It is presumed that the distortion caused by the crystal container and temperature conditions that exist when passing near the phase transformation point generates twins. In other words, it is presumed that as long as this crystal growth method is adopted, twins will occur.

On the other hand, another conventional manufacturing method is shown in FIG. 5(a).
The manufacturing equipment shown schematically in Figure 1 is used. A case will be described in which a Cd0.5 Mn0.5 Te single crystal is grown using this apparatus. Solvent Te5 in quartz crucible 53
6 and the solid crystal raw material (CdMnTe sintered rod) 57' are placed in a vacuum (degree of vacuum ≦1×10-5T) so that they have a predetermined relationship.
orr) sealed container. After that, the THM furnace (Fig. 5(a)
)), the quartz crucible 53 is lowered at a rate of 1 to 5 mm/day, and the single crystal 55 is grown sequentially from the lower end of the quartz crucible 53. The melting point (=800°C) of the crystal is below the phase transformation point (=about 850°C), so it has a zincite-type structure. In this case, since the phase transformation point is not passed during the crystal growth process, twins do not occur. However, in the growth process, crystals are produced while dissolving the solid crystal raw material (CdMnTe sintered rod) 57' in the solvent 56, so thermal changes occur at the solid-liquid interface (continuous temperature fluctuations within the melt). It was difficult to make the entire crystal growth surface into a single crystal (in the low melting point growth process,
The conditions of mass transport and convection are different and are extremely sensitively affected). In addition, the growth speed is extremely slow (1.0 to 5.0 m
m/day), it had not developed as an industrial mass production technology.

0004

[Problems to be Solved by the Invention] Using the conventional manufacturing method of the former, Cd1-X MnX Se and Cd1-X M
When II-VI group compound semiconductors such as nX Te and CdTe are manufactured, although they are suitable for industrial use, there are problems with their crystallinity, for example, they tend to form twin crystals. especially,
In the case of Cd1-X MnX Te single crystal, its crystallinity determines whether it can be used in devices such as short-wavelength optical isolators. In other words, the major challenge is to produce high-quality single crystals that fully satisfy the physical properties required by devices. However, when a semimagnetic semiconductor device is manufactured using a material with twins, there is a drawback that the device cannot be used at all due to poor quality.

On the other hand, using the latter production method, Cd1-X
MnX Se and Cd1-X MnX Te and Cd
When a single crystal of a II-VII group compound semiconductor such as Te is produced, it is possible to solve crystallinity problems such as the tendency to form twins. That is, specifically, semimagnetic semiconductors (Cd1-X MnX Te, Cd1-X MnX S
When e) is produced using the conventional Bridgman method, the melting point is above the phase transformation point, so when it solidifies, it always passes through the phase transformation point where the wurtzite structure changes to the zincite structure. do. It is believed that the residual strain at that time is the cause of twins (for example, R. TRIBOURET
et al, Journal of Crystal
Growth 101 (1990) 131-13
4). However, in the latter conventional manufacturing method,
There is no problem if the entire structure changes to the splenite structure when passing through the phase transformation point during the solidification process from a temperature higher than the phase transformation point. Since the solidification is performed at a temperature lower than the point, it is possible to avoid twin crystals. However, from the point of view of mass production technology, it is a problem because it takes many days to train.

Therefore, the technical problem of the present invention is to solve the problem of semimagnetic semiconductors (Cd1-X MnX Se, Cd1-X MnX
An object of the present invention is to provide a single crystal manufacturing method that can mass produce high quality single crystals of II-VII group compound semiconductors such as Te) and CdTe.

[0007]

[Means for Solving the Problems] According to the present invention, semimagnetic semiconductors (Cd1-XMnX Te, Cd1-X MnX
In a method for producing single crystals of II-VI group compound semiconductors such as At a temperature above the transformation point, hot isostatic press (HOTISOSTATIC PRESS,
A method for producing a single crystal is obtained, which is characterized by a treatment (hereinafter referred to as HIP). According to the present invention, there is obtained a single crystal manufacturing method characterized in that the single crystal rod is covered with powder having the same composition during the hot isostatic pressing treatment. According to the present invention, in the method for producing a single crystal, when performing the hot isostatic pressing treatment, the atmosphere condition is Ar gas, the pressure condition is 500 to 1200 kg/cm2, and the temperature is 880 to 980°C. A method for producing a single crystal is obtained.

[0008]

[Operation] In the present invention, the single crystal rod produced by the Bridgman method is subjected to HIP treatment at a temperature above the phase transformation point, and then the rod is passed through the phase transformation point under external pressure, so that all of the rods are made of zinc ore. By transitioning to the type structure, semimagnetic semiconductors (Cd1-X MnX Te, Cd1-
It becomes possible to mass produce high quality single crystals (XMnXTe).

[0009]

Embodiments Examples of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a method for manufacturing a single crystal according to an embodiment of the present invention, and FIG. 2 is a diagram showing the HI in the manufacturing method of FIG.
It is a figure showing the composition of P device. As a method for manufacturing a single crystal according to an embodiment of the present invention, Cd0.5 Mn0.5 Te
The case where a single crystal is grown will be explained. As shown in FIG. 1, a twinned CdMnTe single crystal is grown using a conventional manufacturing method, and then the CdMnTe single crystal is taken out. Next, place it in the predetermined position of the HIP device shown in FIG. The CdMnTe single crystal 12 is buried in molten CdMnTe sintered powder 11 of the same composition, filled in a refractory crucible 8, and placed on a support stand 13. Further, a heating heater 14 for heating is arranged around the crucible in this furnace. In this state, the temperature and pressure are increased to a predetermined temperature. After maintaining the temperature in the range of 880 to 980°C for 30 minutes or more, it is rapidly cooled within the capacity of the equipment. Furthermore, Ar gas 10 is introduced as an atmospheric gas from an inlet above the furnace. This manufacturing process uses twinned CdM
The temperature of the nTe single crystal is raised to a temperature higher than the phase transformation point, and the temperature is passed through the phase transformation point while applying pressure. Table 1 and FIG. 3 show the crystallinity test results of samples ① to ② obtained by the above manufacturing method. Also, for comparison, the crystallinity test results of sample ① prepared by the conventional method are attached. In addition, ○△× in Figure 3
corresponds to the evaluation in Table 1.

From Table 1 and FIG. 3, it can be seen that the temperature above the phase transformation point and not melting is preferably in the range of 880 to 980°C. On the other hand, pressure≦500kg/cm2
In this case, sublimation of the CdMnTe single crystal becomes more likely to occur,
Defects such as voids will occur inside the crystal, resulting in a significant deterioration of optical properties. If the pressure is 1200 kg/cm2, the stress will be too strong and distortion such as cracks will occur in the CdMnTe, so the pressure should be in the range of 500 to 1200 kg/cm2. It is preferable that the The present inventors believe that the cause of twinning is that there is no problem if all the structure transitions to the zincite structure when passing through the phase transformation point, but points where the wurtzite structure remains partially become twins. ing. That is, the method for producing a single crystal of the present invention prevents thermal strain, which is a result of the influence of latent heat generated when passing through a phase transformation point, from inhibiting single crystal growth, by applying isotropic pressure. By preventing this, twinning can be reduced. As described above, as a result of adopting the single crystal manufacturing method according to the embodiment of the present invention, the crystallinity problem (twinning) is solved, and Cd1-X MnX Te and Cd1-X M
It has become possible to mass produce high quality materials such as nX Se.

[0011]

[Table 1]

0012

[Effects of the Invention] As explained above, the present invention produces a single crystal rod by the Bridgman method, and performs HIP treatment on the single crystal rod at a temperature higher than the phase transformation point, thereby producing a high quality single crystal. It is possible to provide a method for manufacturing a single crystal that allows mass production of.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a method for manufacturing a single crystal according to an example of the present invention.

FIG. 2 is a diagram showing the configuration of a HIP device in the manufacturing method of FIG. 1;

FIG. 3 is a diagram showing the relationship between pressure and temperature of the HIP apparatus according to the embodiment of the present invention.

FIG. 4(a) is a diagram showing an example of a conventional single crystal manufacturing apparatus. (b) is a diagram showing the temperature distribution in the furnace of the single crystal production apparatus of (a).

FIG. 5(a) is a diagram showing another example of a conventional single crystal manufacturing apparatus. (b) is a diagram showing the temperature distribution in the furnace of the single crystal production apparatus of (a).

[Explanation of symbols]

1 Step of vacuum sealing in a quartz crucible 2 Step of crystal growth using Bridgman method 3 HIP
Treatment step 8 Crucible 9 Heat insulating layer 10 Gas 11 CdMnTe sintered powder 12 CdMnTe single crystal with twins 13 Support stand 14 Heater 51 Electric furnace 52 Crucible lifting mechanism 53 Quartz crucible 54 Melt 54' Melt 55 Single crystal 56 Raw material 56' Raw material 57' Solid crystal raw material

Claims (3)

[Claims] [Claim 1] Semimagnetic semiconductor (Cd1-X Mnx
In a method for manufacturing a II-VI group compound semiconductor single crystal such as Te, Cd1-X MnX Se), after a single crystal rod is produced using the Bridgman method, the single crystal rod is A method for producing a single crystal, comprising hot isostatic pressing at a temperature higher than the phase transformation point of a substance constituting the crystal. 2. The method for producing a single crystal according to claim 1, wherein the single crystal rod is covered with powder having the same composition during the hot isostatic pressing treatment. 3. In the method for producing a single crystal according to claim 2, when performing the hot isostatic pressing treatment, the atmospheric conditions are set to A.
In r gas, the pressure is 500 to 1200 kg/cm2,
A method for producing a single crystal, characterized in that the temperature is 880 to 980°C.