JPS62153192A - Method for growing crystal of compound semiconductor - Google Patents

Abstract

PURPOSE:To grow bulk single crystal having high quality and sufficient dimension, by controlling and setting each temperature of seed crystal growth part, a bulk crystal growth part and a growing raw material parat independently and growing the seed crystal in such a way that the tip is made acute. CONSTITUTION:For example, in a method for growing crystal of II-VI compound semiconductor (e.g., ZnS) using no seed crystal, ZnS of a raw material 13 heated by temperature T3' in a third zone Z3 is raised in a molecular state, cooled by a quartz heat sink 10 and a seed crystal nucleus is produced at the tip face of the heat sink 10. Seed crystal 11 is grown around the nucleus as a center and the seed crystal 11 is made acute. Bulk crystal 12 of ZnS is grown from the acute face. Since the formed bulk crystal 12 is grown from the face of the seed crystal 11 having very small area at a constant temperature T2', it receives neither lattice defect nor crystal strain, etc., of the seed crystal 11 and high-quality bulk single crystal having sufficient dimension can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is directed to the production of II-III group compounds (ZnS, Zn5e, etc.) using the sublimation method (sublimation recrystallization method) or the Rodan transport method.

The present invention relates to a method for growing a bulk single crystal of ZnTe+CdSr...).

<Prior art and its problems> Bulk single crystals such as Zn5s and Zn5e have conventionally been grown using methods such as dithering, high-pressure bath melting, sublimation, and iodine transport, which is one of the halogen transport methods. The ZnS crystal obtained by the zero-pressure melting method is grown at a growth temperature of about 1800℃.
), it has a phase transition point in its crystal structure at a temperature lower than had. On the other hand, in the sublimation method and the iodine transport method, growth is performed at a temperature below the phase transition point, so a high concentration of stacking faults can be avoided. Zn stored at the bottom of the growth container (ampule)
The S raw material 2 grows crystals using the ZnS seed crystal 3 located at the tip of the seed crystal push rod 6 in the seed crystal holding tube 5 as a nucleus, and becomes a ZnS bulk grown crystal 4.

However, in such a method, the bulk after growth is grown directly on the vessel wall of the ampoule L or on the seed crystal 3 during the temperature gradient due to the natural gradient (indicated by the straight line 7 in the figure). Crystal 4 takes on the disordered (low crystallinity) state that exists at the initial stage of growth, and often contains twins and voids.Furthermore, due to the temperature distribution mentioned above, the growth conditions change as it grows. Because of the gradual change, it was not possible to obtain a homogeneous single crystal with a sufficiently large diameter. In other words, as the temperature of the crystal growing part and the raw material part change as the crystal grows, the temperature difference between the two also stops naturally, and the resulting bulk crystal 4 has its limits in terms of shape and size. there were. Therefore,
It is difficult to obtain 15 or more single crystals with good reproducibility, which is the minimum requirement for practical use, and moreover, it has been impossible to obtain homogeneous high-quality crystals. These problems arise when the material is
This phenomenon occurs not only in the case of nS but also in many ■-■ group compounds.

<Objective of the Invention> The present invention has been made in view of the above points, and is intended to provide a constant temperature range during the growth of ■-■ group compound semiconductors such as ZnS and Zn5e in an ampoule by the sublimation method and the halogen transport method. The object of the present invention is to provide a method for growing a bulk single crystal, which allows a homogeneous, high-quality single crystal to be obtained through crystal growth.

<Summary of the Invention> The crystal growth method of the present invention is based on a seed space in which crystal grains are selected by forming a neck before the crystal elongating from a seed crystal (including a seed crystal due to natural nucleation) thickens as a bulk. (or a heat sink space in the case of natural nucleation), a growth space where selected crystal grains grow steadily under certain conditions (temperature, degree of supersaturation), and a raw material space where a certain amount of raw material vapor can be supplied during growth. High quality and high productivity are achieved by controlling each zone's temperature distribution independently, and more specifically, it is an angle that enables local heat absorption in the seed crystal (or heat sink for seed crystal generation). By heating (cooling) both the growth space and the raw material space independently in the seed crystal part using the structure, tapering necking growth is produced, and steady growth is generated from the tip (terminal) crystal under certain conditions. The temperature distribution is set to enable crystal growth. The present invention can be applied not only to systems with ampoule-like closed tube structures, but also to growth in open tube systems that can be opened and closed, using the same principle.

<Example> The present invention will be explained in detail by taking as an example the single crystal growth of ZnS by the iodine transport method.

Example (1) Case in which one type of crystal is not used (naturally nucleated crystal is used by a heat sink) Figure 1 is a block diagram of a crystal growth apparatus using an iodine transport method to explain one example of the present invention. .

The quartz ampoule 8 consists of a hollow body part with a diameter of 30 cm and a length of loom, and a hollow neck part 9 with a necking length of 10 + o+, which is thinner than the body part, and a quartz heat sink 10 is hung from above on the neck part 9 circles. The heat sink 10 is used for natural seed crystal nucleation, and a seed crystal 11 obtained by natural nucleation is formed at its tip. The diameter of this seed crystal 11 gradually decreases as it moves downward from the neck, and reaches its minimum diameter at the tip. A grown crystal 12 is obtained following this tip. Raw material 13 is placed at the bottom of quartz ampoule 8.
A ZnS material is placed thereon. Further, the quartz ampoule 8 is provided with a temperature distribution shown by a curve 14 in the vertical direction. The temperature in the figure is set to T1'<T3', and the temperature in the first zone Z1 of the area corresponding to the seed crystal 11 is
Temperature control is performed independently and individually in the second zone Z2 corresponding to the grown crystal 12 and the third zone Z3 corresponding to the raw material 13, respectively. , the first zone Z is automatically controlled to a temperature of TI' to T2', the second zone Z is automatically controlled to a temperature of T', and the third zone z3 is automatically controlled to a temperature of T3'. When growing crystals using ZnS as the raw material 13, T I
', T2'*T3 temperature is 600~1000℃
Appropriately selected within the range.

Raw material 13 heated at temperature T3' in third zone Z
ZnS becomes molecular and rises, and the ZnS of quartz heat sink 1
0, and a seed crystal portion is generated on the tip surface of the heat sink 10. A seed crystal 11 grows around this nucleus, but
The growing portion of the seed crystal 11 has a temperature gradient, and the temperature gradually increases as it moves downward. Therefore, the probability of spontaneous nucleation decreases in regions where the temperature is high, and the seed crystal 11 obtained on the lower end surface of the heat sink 10 becomes sharp with a diameter that gradually decreases downward. This tip surface f)Z
An nS bulk crystal 13 is grown by the iodine transport method. The bulk crystal 13 that is formed grows at a constant temperature T21 from the surface of the seed crystal 11 with an extremely small area, so it does not inherit the lattice defects or crystal distortion of the seed crystal 1 and has good crystallinity. It becomes a hexagonal crystal.

In addition, the crystal size can be increased, and it is possible to easily obtain crystals of IC- or higher.Example (2) When using a type of crystal This is the configuration and origin of the crystal growth apparatus used. In this embodiment, a seed crystal 11 is attached in advance to the lower end surface of a quartz heat sink 10, and a seed crystal I+ is grown using this seed crystal 11 as a nucleus. The conditions were the same as in Example (]) except that the seed crystal 11 was installed in advance. The seed crystal 11 was grown downward so that the diameter became smaller in sequence in the same temperature range of the first zone as in Example (11). The lower end surface has a sharpened minute area.The bulk crystal 12 is grown on this lower end surface in the temperature range of the second zone (temperature T2') in the same manner as in Example 11 above.The ZnS raw material 13 for crystal growth is At the bottom of the ampoule 8, the temperature is set in the third zone temperature range (temperature T3').

In this example as well, a bulk crystal with good crystallinity can be obtained as in Example +1+. In addition, each of the above actual fan examples is described as an ampoule arrangement when using a vertical furnace, but when using a horizontal furnace or a rotatable furnace, the upper and lower positions of the seed crystal and raw material (Tenri's The relationship can be arbitrarily selected. <Effects of the Invention> As explained above, according to the present invention, necking during seed crystal elongation and crystal growth can be performed independently and under constant steady conditions regardless of the presence or absence of a seed crystal. As a result, bulk single crystals of high quality and sufficient dimensions can be obtained, making them industrially practical as crystal materials for compound semiconductor devices and crystal growth substrates. This makes it possible to provide a single crystal.

[Brief explanation of drawings]

FIG. 10 and FIG. 2 are block diagrams of a growth apparatus provided for detailed explanation of the present invention, respectively. FIG. 3 is a block diagram showing a crystal-growing quartz ampoule used in the conventional iodine transport method and the temperature distribution during growth. l... Quartz crystal growth container (ampule), 2... Raw material ZnS, 3... Seed crystal Zn5.5... Seed crystal holding tube, 6... Seed crystal push rod, 8... Quartz crystal growth container (ampule), 9... neck portion, IO... quartz heat sink, 11... seed crystal ZnS, 12... growing crystal ZnS, 13... raw material ZnS. Agent Patent Attorney Aihiko Fukushi (and 2 others) Tco Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a crystal growth method for II-VI compound semiconductors using the sublimation method or halogen transport method, the temperatures of the seed crystal growth section, bulk crystal growth section, and growth raw material section are independently controlled and set, and the seed crystal is placed at the tip. A method for growing a compound semiconductor crystal, the method comprising growing a bulk crystal from the tip of the seed crystal so that the seed crystal becomes sharp.