JPS6287487A - Formation of single crystal doped with impurity - Google Patents

Abstract

PURPOSE:To obtain a compound single crystal uniformly doped with an impurity, by using a reaction product of a halogen (compound) with at least one constituent element of the single crystal as a transporting substance. CONSTITUTION:At least one of constituent element of a single crystal, e.g. ZnS or CdS, is mixed with a doping impurity, e.g. Mn or Cr and, as necessary, heat-treated at 800-900 deg.C for several hours. The resultant mixture 2 is then put in a single crystal growth vessel 1 hermetically sealing a halogen (compound) selected from Cl, Br, I or hydrides thereof and heated at a temperature gradient to provide the maximum temperature in the mixture part 2. The aimed single crystal doped with the impurity is grown on the substrate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming a compound single crystal homogeneously doped with impurities.

(Prior art and its problems) Conventionally, methods for forming impurity-doped crystals include ion implantation into thin films, chemical vapor deposition (CVD), and other vapor phase growth methods, as well as liquid phase growth, The Zollinman method does exist. Some of these are crystals that have been established as large-scale production technology, and most of them are crystals made of elements, and compound semiconductors made of two or more elements. If the above method is used to dope a single crystal of two or more elements with impurities, various problems will occur such as segregation of impurities and compositional deviation of the mother crystal. In particular, in n-vt group or m-v group compounds, the vapor pressure of the constituent elements varies greatly depending on the type of element, and problems such as compositional deviation during crystal formation become even more serious and complicated.

Among these problems, several single crystal formation methods have been proposed to prevent compositional deviations in compound crystals. Molecular beam epitaxy (MBE) is a typical method. This method involves forming thin film single crystals by crystallizing compound elements layer by layer alternately. In principle, the MIIE method can yield high quality thin film single crystals and allows for controlled impurity topping. .However, currently (
1: However, in this method, the target elements are limited and very expensive equipment must be used.

Further, a vapor phase chemical growth method has also been proposed in which a chemically active halogen alone or a halogen compound is used as a chemical transport substance and crystal growth is performed through the vapor phase. This method utilizes the chemical properties of a single halogen or a halogen compound, and grows a compound single crystal at a low temperature below the original melting temperature of the growing single crystal. However, this method is used only for forming a highly pure compound single crystal, and is not used for doping with impurities.

(Structure of the Invention) The present invention uses a single halogen or a compound thereof for impurity doping. That is, the present invention provides a method for forming an impurity-doped compound single crystal by using an elemental halogen and/or a reaction product of a halogen and at least one of the constituent elements of the single crystal as a transport substance.

Halogen elements are generally rich in chemical activity due to their electronic structure, and about 80 metal elements, which are composed of almost all transition metal elements and group B metals, are compounds with one or more halogen elements. form. These compounds exist in various phases such as ionic crystals, molecular crystals with low melting points, and liquids at room temperature, and the types of compounds and the types of states in which they exist are extremely diverse.

These facts show that if a suitable single halogen or a halogen compound is used as a transport material during single crystal vapor phase growth, impurities can be transported simultaneously with the mother crystal raw material in a relatively wide range of concentrations. It is possible to grow the mother crystal at a relatively low temperature below the melting point of the mother crystal.

Usable halogens include fluorine, chlorine, bromine, and iodine, but chlorine, bromine, iodine, or hydrides thereof are preferred because they are easy to handle.

Examples of reactants of halogen and at least one of the single crystal constituent elements include ZnI2, CdL, ZnCρ2, CdCl27, etc. when the single crystal constituent element (impurity or doped) is ZnS, CdS, etc. It will be done.

As the mother crystal of the compound single crystal, I-Vl group compounds, 11
-■ group compound, n-v group compound, n-vr group compound, I
Examples thereof include -V group compounds, III-Vl group compounds, IV-Vl group compounds, MA-Vl group compounds, V-IV group compounds, and group II mixed crystals. In addition, impurities doped into the mother crystal include transition metals such as Mn, Cr, and V, Nd
All elements that form compounds with halogens, including lanthanide metals such as Pm55m and Pm55m, can be targeted.

The method for forming a compound single crystal of the present invention can be applied to a conventional gas phase chemical reaction method using the above halogen or halogen compound as a transport substance.

Embodiments of the present invention will be described with reference to the drawings.

As a raw material for growing compound single crystals doped with impurities, a mixture of mother crystal powder (ZnS) and doping impurities (Mn, manganese) is used.
Heat treatment is performed at 00 to 900°C for several hours. This raw material is placed in one side (2) of a closed single crystal growth container (1), and the container is placed in the furnace so that this part has the highest temperature. The raw material section (
A temperature gradient is set with 2) as the highest temperature, and a single crystal grows on the substrate (3). Crystals are grown from the lowest temperature region, and a single halogen or a halogen compound is sealed inside the single crystal growth container. It is possible to grow single crystals of impurity-doped compounds either vertically or horizontally, regardless of the shape or type of furnace.

Further, in this example, the reaction was performed in a closed container, but in an open tube system, the same effect as in the above example can be produced by causing the halogen compound to flow from the raw material section to the single crystal growth section.

The results obtained for cubic zinc sulfide (ZnS:Mn'') doped with a small amount of manganese, which was grown as a single crystal by the method described above, will be described as an example of the above embodiment.

Single-crystal grown ZnS: The Mn''+ concentration in Mn'' is approximately 0.09% compared to the Mn''+ concentration in the raw material polycrystal.
It turns out that it is 7 times as large and can be considered almost I.

Considering the experimental error of about ±2%, this shows that the impurities in the grown crystal are doped with almost the same composition as the raw material, and it is possible to fully control the amount of impurity doping. means.

Further single crystal grown ZnS: Mn in Mn'+
`` ``It was found from the results of the electron spin resonance (shown in Figure 2) experiment that the local structure surrounding the ion has cubic symmetry, but this is because the Mn'+ ion has very good symmetry. This means that there is no intrusion of impurity atoms into the interstitial space that would cause deterioration of crystallinity, indicating that a high-quality crystal is obtained. This is consistent with the experimental results of X-ray diffraction (shown in Figure 3).

(Effects of the Invention) As explained in detail above, according to the present invention, a gas phase chemical transport method using a simple halogen or a halogen compound as a chemical transport substance, which has been conventionally used as a method for growing pure compound single crystals, is used. As a result, it was found that the amount of impurities can be controlled well and the growth can be performed at a temperature lower than the melting temperature of the parent compound crystal without impairing the crystallinity of the parent crystal.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a reaction vessel used in Examples. In the figure, (1) shows a single crystal growth container, (2) shows a raw material part, and (3) shows a substrate. FIG. 2 is a diagram showing the electron spin resonance of the manganese-doped cubic zinc sulfide obtained in the example. (9GH2
, 100KHz modulation, room temperature measurement) = Figure 3! An X-ray transmission urani photograph of the SO material is shown. , = 8 - Figure 3 Procedural amendment written format) % formula % 1 Indication of case Patent application No. 229381 of 1985 2. Name of invention Impurity-doped single crystal formation method 3. Person making amendment Relationship with case Patent Applicant Address 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Name
(504) Sharp Corporation Representative Sa
Date of amendment order for Haku Asahi 4 and Agent 5: January 28, 1986 (Shipping 1)
6. Subject of amendment Column of brief explanation of the drawings in the specification and Figure 3, Figure 7 of the drawings, Contents of amendment (1) Column of ``V brief explanation of drawings'' of the specification, page 8, No. 7
In the line, the text "X-ray transmission urae photograph" should be corrected to "X-ray photograph." (2) Figure 3 of the drawings attached to the specification is corrected as shown in the attached sheet. Figure 3 above

Claims (1)

[Scope of Claims] 1. A method for forming an impurity-doped compound single crystal by using a reaction product of an elemental halogen and/or a halogen compound with at least one constituent element of the single crystal as a transport substance. 2. The method according to item 1, wherein the halogen is chlorine, bromine, iodine, or a hydride thereof. 3. Impurity-doped compound single crystal is impurity (M)-doped zinc sulfide selenide mixed crystal (ZnSxSe_1_-_X:M,
The method according to item 1, wherein 0≦X≦1).