JPH0873300A - Method for growing ZnSe single crystal - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a method for efficiently growing a large-sized and high-quality ZnSe single crystal with high reproducibility by suppressing variations in growth rate. [Constitution] A raw material polycrystal and a group VI element are vacuum-sealed in one end of a reaction tube, and the sublimation temperature (T) of the polycrystal is set to 1050 to 142.
Within the range of 5 ° C., the addition amount (ΔN) of the group VI element is adjusted to the reaction tube 1c.
It is adjusted to 5 × 10 ⁻⁵ g or more per m ^3, and the difference (ΔT) between the crystal precipitation temperature and the sublimation temperature is 50 ° C. or less, 1 × 10 ⁻⁷ ≦ Δ
This is a method of growing a ZnSe single crystal while adjusting the range of T × 10 ^{−18500 / T} ÷ (ΔN) ^3/2 ≦ 5 × 10 ⁻⁷ .

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for growing a ZnSe single crystal by a sublimation method.

[0002]

2. Description of the Related Art ZnSe crystals are roughly classified into four types, that is, a melt growth method, a solid phase growth method, a solution growth method and a vapor phase growth method. Among them, the vapor phase method (sublimation method) has been tried for a long time, for example, JOUNAL OF CRYS.
As seen in TAL GROWTH 94 (1989) P1-P5, a single crystal having a size of about 10 mm square is obtained. This method is 5g
The ZnSe raw material polycrystal and the ZnSe single crystal as a seed crystal are placed at both ends of a quartz reaction tube having a diameter of 20 mm and a length of 70 mm, sealed in vacuum, and heated to 1070 ° C. in an electric furnace. At this time, the temperature of the seed crystal is adjusted to be about 10 ° C. lower than the temperature of the polycrystalline ZnSe raw material, and a ZnSe single crystal is grown on the seed crystal.

[0003]

However, in the above method, the crystal growth temperature is increased, or the temperature difference ΔT between the raw material polycrystal portion and the single crystal growth portion is increased to increase the growth rate, or conversely. Although the growth rate can be reduced by lowering the growth temperature or decreasing ΔT, it was difficult to uniformly control the crystal growth rate. As in the literature above,
If the crystal growth is performed at the same growth temperature and ΔT, the growth rate greatly varies. Moreover, if the growth rate is too high, there is a problem that a single crystal does not grow and a polycrystal is generated.

Therefore, the present invention solves the above-mentioned drawbacks,
An object of the present invention is to provide a method for suppressing large variations in growth rate and growing a large-sized, high-quality ZnSe single crystal with good reproducibility.

[0005]

The present invention has succeeded in solving the above problems by adopting the following constitution. (1) Vacuum seal a polycrystalline ZnSe raw material at one end of the reaction tube,
In the method of growing a ZnSe single crystal by heating the one end to the sublimation temperature of the polycrystal and the other end to the precipitation temperature of ZnSe, a Group VI element (ΔN) is added to the ZnSe polycrystal in the reaction tube. Enclose 5 × 10 ⁻⁵ g or more per 1 cm ^{3 of} reaction tube volume, and set the sublimation temperature (T) to 1050 to 1425.
Within the range of ℃, the difference between crystal precipitation temperature and sublimation temperature (ΔT) is 5
0 ° C or less and 1 × 10 ^-7 ≦ ΔT × 10 ^{-18500 / T}
÷ (ΔN) ^3/2 ≦ 5 × 10 ⁻⁷ A method of growing a ZnSe single crystal, characterized by adjusting the range.

(2) A method of growing a ZnSe single crystal in the method of growing a ZnSe single crystal according to the above (1), characterized in that a ZnSe polycrystal recrystallized by a sublimation method is used as a raw material. (3) In the method for growing a ZnSe single crystal according to (1) above, the ZnSe polycrystal is crushed into a powder, and the temperature is 500 ° C. in vacuum.
A method for growing a ZnSe single crystal, which comprises using a raw material obtained by heating at the above temperature for 1 hour or more. (4) In the method for growing a ZnSe single crystal according to the above (1), a hydride of Zn and Se vapor are used as raw materials, and the temperature is 500 ° C.
A method of growing a ZnSe single crystal, characterized in that a ZnSe polycrystal synthesized at the above temperature is used as a raw material.

[0007]

The present inventor has studied various causes of the variation in the crystal growth rate in the sublimation method, and in the course of studying the source polycrystalline ZnSe.
The composition ratio of Zn and Se in Example 1 was deviated from 1: 1, and it was found that there was excess Zn or Se. As a countermeasure against this, crystal growth was carried out with the composition deviation of the raw material polycrystalline ZnSe being as small as possible, but it was not possible to reduce the variation in growth rate.

Therefore, when Zn or Se is added to the raw material polycrystalline ZnSe instead of reducing the compositional deviation of the raw material polycrystalline ZnSe, variations in the crystal growth rate can be suppressed and stable crystal growth can be achieved. Found that you can do. This is because by adding Zn or Se in an amount sufficiently larger than the amount of Zn or Se corresponding to the deviation of the composition of the raw material polycrystalline ZnSe, the raw material polycrystalline ZnSe
It has become possible to reduce the influence of the compositional deviation of.

In ZnSe crystal growth, when Zn is added, the growth rate is remarkably reduced.
It is considered that this is because the crystal growth by the sublimation method reversibly proceeds according to the following reaction formula and Se exists as Se ₂ in the gas phase. ZnSe (s) = Zn (g) + (1/2) Se ₂ (g)

That is, it has been found that the addition amount of Zn or Se is 5 × 10 ⁻⁵ g or more per 1 cm ^{3 of} the reaction tube volume, which has the effect of stabilizing the growth rate. It has been found that the larger the addition amount, the smaller the variation in the crystal growth rate, but the growth rate stabilizes as the addition amount increases, but the growth rate becomes extremely slow. In particular, when the amount of Zn added was increased, the degree of decrease in the growth rate was extremely large.

Therefore, the inventors of the present invention added Se, whose growth rate is relatively slow to decrease, and added the addition amount (ΔN),
By maintaining a constant relationship between the heating temperature (T) of the raw material polycrystal, the difference between this heating temperature and the crystal precipitation temperature (ΔT), and ΔT, T, and ΔN, variations in crystal growth rate can be reduced. It was possible to control the growth rate and to secure an appropriate growth rate, and succeeded in growing a high-quality large ZnSe single crystal with high yield.

That is, using a quartz reaction tube, 1050-1
When the raw material polycrystal is heated to sublimate in the range of 200 ° C., the excess amount of Se (ΔN) is sealed in at 5 × 10 ⁻⁵ g or more per 1 cm ³ of the reaction tube volume, and the difference between the crystal precipitation temperature and the sublimation temperature (ΔT ) ^Is adjusted to 50 ° C. or lower, and 1 × 10 ⁻⁷ ≦
It is optimal to adjust within the range of ΔT × 10 ^{−18500 / T} ÷ (ΔN) ^3/2 ≦ 5 × 10 ⁻⁷ . Raw material polycrystal heating temperature is 1
Below 050 ° C, the growth rate becomes too low,
If the temperature exceeds 00 ° C, the quartz reaction tube is softened, which hinders crystal growth. Further, even if the temperature difference (ΔT) is larger than 50 ° C., there is no effect of increasing the growth rate, and polycrystals are easily generated. Then, by adjusting the range of the excess amount (ΔN) of Se, it is possible to suppress the variation of the growth rate to be low and maintain the reproducibility of crystal growth high. When the ZnSe crystal was grown under the above conditions when using an ampoule having an inner diameter of 20 mm, stable growth was possible at a growth rate of 0.1 to 0.5 g / day.

Instead of a quartz reaction tube, a material that does not soften at temperatures below 1425 ° C. and is impermeable to gas, such as Mo.
When a ZnSe crystal is grown using a metal reaction tube or the like, the heating temperature of the raw material polycrystal is 1200 to 1425 ° C.
Adjust to the range of, and set the excess amount of Se (ΔN) to the reaction tube volume 1
5 × 10 ⁻⁵ g or more per m ^3, the difference between crystal precipitation temperature and sublimation temperature (ΔT) is adjusted to 50 ° C. or less, and 1 × 1
0 ^-7 ≤ ΔT × 10 ^{-185 00 / T} ÷ (ΔN) ^3/2 ≤ 5 × 10 ^-7
By adjusting to the range described above, an appropriate growth rate can be secured as in the above. The heating temperature 1425 ° C. of the raw material polycrystal was determined in consideration of the phase transformation point of the ZnSe crystal.

In order to make the crystal growth rate stabilizing method according to the present invention more effective, it is preferable to use a raw material polycrystal having a small composition deviation. One method is to use a polycrystal recrystallized by a sublimation method as a raw material, and the other method is to powderize ZnSe polycrystal, fill the quartz tube with vacuum, and evacuate at a temperature of 500 ° C or higher. A method of using a polycrystal heated for 1 hour or more as a raw material, and yet another method is a method of using a ZnSe polycrystal synthesized from hydrogen selenide and zinc vapor as raw materials at a temperature of 500 ° C. or higher as a raw material. It was confirmed that the use of these raw materials further improved the stabilization of the growth rate. In particular, the effect was remarkable in the region where the excess amount of Se (ΔN) was relatively small.

[0015]

【Example】

(Synthesis example 1 of ZnSe polycrystal) Purity 99.999% each
Zn and Se of 1/10 mol are weighed in 1/10 mol, and the inner diameter is 20 m.
A quartz tube having a length of m and a length of about 120 mm was filled with the tube, and after being replaced with argon, the tube was vacuum-sealed at about 10 ⁻⁸ torr. This is 10
It was heated and held at 00 ° C. for 3 to 4 days and then cooled in a furnace to room temperature to obtain a ZnSe polycrystal.

Comparative Example 1 A ZnSe single crystal was grown by a sublimation method using the ZnSe polycrystal of Synthesis Example 1 as a raw material. As shown in Fig. 1, a quartz crystal having an inner diameter of 20 mm and a length of 100 mm was provided with a seed crystal having a ZnSe single crystal (100) face as the front surface at one end, and the above ZnSe polycrystal was provided at the other end. Vacuum sealed at ^-8 torr. Then, this quartz ampoule was put into a crystal growth furnace having a temperature distribution shown in FIG. 2, the raw material heating temperature was 1040 ° C., and the seed crystal temperature was 1
It was set at 020 ° C. and grown for 1 week. Crystal growth was performed 5 times under the same conditions, and the results are shown in Table 1.

[0017]

[Table 1]

Example 1 A ZnSe single crystal was grown by a sublimation method using the above ZnSe polycrystal as a raw material and adding an excess amount of Se. As shown in Figure 1, inner diameter 20mm, length 1
A ZnSe single crystal (1
The seed crystal having the (00) plane as a surface is arranged, and the above-mentioned Zn is formed at the other end.
Se polycrystal is arranged and the excess Se shown in Tables 2 to 4 is used.
^Was added and vacuum sealed at about 10 ⁻⁸ torr. Then, the heating temperature of the raw material is set to 3 types of 1040 ° C., 1120 ° C. and 1200 ° C., and the temperature of the seed crystal is set to 20 from the above heating temperature.
The temperature was set low, and the cells were grown for 1 week. Crystal growth was performed 5 times under the same conditions, and the results are shown in Tables 2-4.

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

As can be seen from Tables 2 to 4, the larger the amount of Se added, the smaller the variation in growth rate, but the slower the growth rate. The growth condition of the present invention is 1
× 10 ^-7 ≦ ΔT × 10 ^{-18500 / T} ÷ (ΔN) ^3/2 ≦ 5 × 1
In the range satisfying 0 ^-7 , the excess Se addition amount is 5 × 10 ^-5 g /
In cm ^-3 , the heating temperature of the raw material polycrystal is in the range of 1040 ° C, and a single crystal is almost grown, but it is outside this range 1
At 120 ° C and 1200 ° C, all polycrystals are formed. When the excess Se is 2 × 10 ⁻⁴ g / cm ⁻³ ,
The heating temperatures 1040 ° C. and 1120 ° C. of the raw material polycrystal fall within the range, and single crystals grow in all of them, but polycrystals are formed at 1200 ° C. outside this range. Further, when the excess Se addition amount is 5 × 10 ⁻⁴ g / cm ⁻³ , the heating temperatures of the raw material polycrystals are all within the range of 1040 ° C., 1120 ° C. and 1200 ° C. Growing.

Example 2 In Example 1, excess Se was used.
The amount of addition was 2 × 10 ⁻⁴ g / cm ⁻³ , and the temperature of the seed crystal (that is, the difference ΔT between the heating temperature and the seed crystal temperature) was changed at the heating temperature of the raw material polycrystal of 1120 ° C. 1
Crystal growth was performed in the same manner as in. The results are shown in Table 5. When ΔT exceeds 50 ° C., no significant change in the growth rate is observed, but it can be seen that all are polycrystallized.
That is, in order to grow a single crystal, ΔT needs to be 50 ° C. or lower.

[0024]

[Table 5]

Example 3 Using the PBN crucible and the Mo outer crucible shown in FIG. 3, raw material polycrystalline ZnSe and ZnSe single crystal seed crystals were placed at both ends of the crucible, and an excessive amount of Se was added to the crucible.
After evacuating to 0 ^-6 torr and vacuum-sealing, it was put into a furnace heated by a carbon heater to perform crystal growth. The results are shown in Tables 6 and 7. As is clear from Tables 6 and 7, S
By adding more e (5 × 10 ⁻³ g / cm
^-3 ), the variation in growth rate was almost eliminated.
Even if Se is further added and the heating temperature of the raw material is close to the phase transformation point (1425 ° C.), the growth rate becomes extremely slow, which is not preferable.

[0026]

[Table 6]

[0027]

[Table 7]

Although the crucible made of Mo was used as the outer crucible, any material other than Mo can be used as long as the crucible does not soften in the temperature range of 1200 to 1425 ° C. and does not pass gas. When the raw material polycrystal is heated at 1200 ° C. or lower, even if the crystal growth is performed under the conditions of Example 2, variation in the growth rate does not pose a problem.
It is advantageous to use a quartz reaction tube, which is advantageous in terms of cost.

Example 4 As raw material polycrystalline ZnSe,
The following three kinds of raw materials were prepared, and Zn was prepared in the same manner as in Example 1.
Se crystals were grown. The amount of excess Se added is 2 ×
10 ⁻⁴ g / cm ⁻³ , heating temperature of raw material polycrystal is 1120
℃, the difference between the heating temperature of the raw material polycrystal and the temperature of the seed crystal (Δ
T) was adjusted to 20 ° C. The results are shown in Table 8.
Comparing with the results of Example 1, it can be seen that the variation of the growth rate is smaller when the raw materials of Raw Material Preparation Examples 1 to 3 are used.

(Raw Material Preparation Example 1) Using the raw material polycrystalline ZnSe obtained in Synthesis Example 1, without using a seed crystal, the raw material polycrystalline Z
nSe was heated and sublimated at 1120 ° C., the temperature of the crystal precipitation portion was set to 1070 ° C., and other conditions were the same as in Comparative Example 1, and recrystallization was performed by a sublimation method to prepare a raw material.

(Raw Material Preparation Example 2) The raw material polycrystalline ZnSe obtained in Synthesis Example 1 was crushed and filled in a quartz tube, and while being evacuated to 3 × 10 ⁻⁶ Torr, heated at 500 ° C. for 1 hour to obtain a raw material. did.

(Raw material preparation example 3) Hydrogen selenide gas and zinc gas were poured into a quartz tube heated to 500 ° C., and raw material polycrystalline ZnSe was produced in the quartz tube.

[0033]

[Table 8]

[0034]

According to the present invention, by adopting the above-mentioned constitution, it is possible to reduce the variation of the crystal growth rate without lowering the growth rate, and it is possible to obtain a large-sized Z with good reproducibility.
It enabled the growth of nSe single crystals.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a quartz ampoule used in Examples 1, 2, 4 and Comparative Example 1.

FIG. 2 is a diagram showing a structure of a growth furnace used in Examples 1, 2, 4 and Comparative Example 1 and temperature distribution in the furnace.

FIG. 3 is a conceptual diagram of a Mo-made ampoule used in Example 3.

FIG. 4 is a diagram showing the structure of a growth reactor used in Example 3.

Claims (4)

[Claims] 1. A ZnSe raw material polycrystal is vacuum-encapsulated in one end of a reaction tube, the one end is set to a sublimation temperature of the polycrystal, and the other end is set to Z.
In a method of growing a ZnSe single crystal by heating to a nSe precipitation temperature, in addition to ZnSe polycrystal in the reaction tube, a group VI element (ΔN) is added in an amount of 5 × per 1 cm ³ of reaction tube volume.
Enclose at least 10 ⁻⁵ g and set the sublimation temperature (T) at 1050 to
In the range of 1425 ° C, the difference between the crystal precipitation temperature and the sublimation temperature (Δ
T) to 50 ° C. or lower, and 1 × 10 ⁻⁷ ≦ ΔT × 10
^{-18500 / T} / (ΔN) ^3/2 ≦ 5 × 10 ⁻⁷ A ZnSe single crystal growth method characterized by adjusting the range. 2. The method for growing a ZnSe single crystal according to claim 1, wherein a ZnSe polycrystal recrystallized by a sublimation method is used as a raw material. 3. The method for growing a ZnSe single crystal according to claim 1, wherein a ZnSe polycrystal is crushed into a powder and heated in vacuum at a temperature of 500 ° C. or higher for 1 hour or more, and a raw material obtained is used. A characteristic method of growing a ZnSe single crystal. 4. The method for growing a ZnSe single crystal according to claim 1, wherein Zn hydride and Se vapor are used as raw materials.
A method for growing a ZnSe single crystal, characterized in that a ZnSe polycrystal synthesized at a temperature of 500 ° C. or higher is used as a raw material.