JPS62288185A - Production of compound semiconductor crystal - Google Patents

Abstract

PURPOSE:To make it possible to produce compound semiconductor crystal having a uniform composition and to add an impurity having large segregation to the crystal uniformly, by producing the crystal by a combined method of a zone melting method and recrystallization method. CONSTITUTION:An ampul 21 is inserted into a fixed position in a furnace 23 in a state wherein an alloy ingot 22 is set at the upper part in the ampul 21. Temperature is raised in such a way that the temperature of the furnace 23 is >= liquid phase formation temperature TL between point P and point Q. Then, the ampul 21 is lowered in direction B. The ingot 22 is melted from a lower end part 22A, melt drops 25 thereof are solidified at a bottom part 21A of the ampul 21 to give crystal, which is formed toward the top part. When the top end part of the ampul 21 reaches the point Q, drop of the ampul 21 is stopped, the temperature of the furnace 24 is adjusted in such a way that the temperature of the whole ampul 21 is a temperature lower than solid phase formation temperature Ts, the ampul is kept in the state for about 30 days and the material is recrystallized. Compound semiconductor crystal having a uniform composition is formed.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Summary] Mercury, cadmium, tellurium (Hg l-X Cd x
A method for growing a multi-compound semiconductor crystal such as T e ) with a uniform composition, and even when an impurity material with a large segregation coefficient is added to the crystal, it is added in a uniform state into the crystal. Then, the ampoule filled with the compound semiconductor crystal forming material is made into a melt in a temperature range higher than the liquidus temperature of the forming material, and the formed melt is in the form of droplets,
After dropping the material dropwise into a region lower than the solidus temperature to rapidly solidify it, it is further recrystallized in a temperature region just below the solidus temperature.

[Industrial application field]

The present invention relates to a method of manufacturing a compound semiconductor crystal, and more particularly to a method of manufacturing a compound semiconductor crystal in which even when an impurity having a uniform composition and a large segregation coefficient is added, the impurity is uniformly added into the crystal.

Mercury, cadmium,
Multi-compound semiconductor crystals such as tellurium (Hg, Cd, Te) are used.

In such a compound semiconductor crystal, an element having a uniform composition and a large segregation coefficient with respect to the compound semiconductor crystal, such as arsenic (As) or antimony (Sb), is used to fabricate an infrared sensing element. In some cases, it may be necessary to add impurity atoms, and even in that case, it is desired that the impurity atoms be added to the crystal at a uniform concentration.

[Conventional technology]

Conventionally, as a method for manufacturing a multicomponent semiconductor crystal such as Hg+-xCdxTe, as shown in FIG.
-x Cd
is sealed in an ampoule 2 with a sharp tip, the ampoule 2 is inserted into a heating furnace 3, and after melting the forming material, the ampoule 2 is sealed.
There is a Bridgman method in which the melt of the forming material is solidified from the tip while descending in the heating furnace 3 along the direction of arrow A to obtain the Hg-CdxTe single crystal 4.

Further, a container filled with the forming material is heated to form a melt of the forming material, the melt is rapidly solidified, and the solidified material is heated to the solidus temperature of the forming material to form a melt of the forming material. There is a recrystallization method that recrystallizes materials.

Further, as shown in FIG. 4, a crystal forming material 11 is sealed in an ampoule 12, and the ampoule 12 is inserted into a heating furnace 13 having a high temperature region higher than the melting temperature of the forming material. A molten zone 14 is formed in the ampoule 1.
There is a zone melting method in which the melted zone 14 is moved from one end to the other end by moving the melted zone 14 downward along the direction of the arrow B to form a single crystal.

Furthermore, as a modification of this zone melting method, for example, when forming a single crystal of Hg + -xCdXTe, Hg + -xCdXTe is formed at a temperature near the melting point of tellurium, which has a low melting point.
A traveling heater method in which only tellurium among the crystal forming materials is melted to form a tellurium solvent, and this solvent is moved from one end of the forming material to the other by lowering an ampoule to obtain a single crystal. There is a (TMM) law.

[Problem that the invention seeks to solve]

By the way, in the phase diagram of a crystal of Hg*-x Cd , the composition of the melt immediately after melting the crystal-forming material,
A phenomenon of segregation occurs in which the composition of the melt varies greatly between the composition of the remaining melt in which crystals are grown from this melt.

Therefore, in crystals grown by the conventional zone melting method or Bridgman method, the composition tends to fluctuate in the direction of the crystal growth axis, resulting in the problem that crystals with uniform composition cannot be obtained.

Further, in this method, when arsenic (As) atoms, which are highly segregated, are added to the crystal forming material, there is a problem that they are not added at a uniform concentration within the formed single crystal.

In addition, in the above-mentioned recrystallization method, in the pre-process step of melting and solidifying the forming material to form an alloy of the forming material, if the molten material is rapidly cooled, the solidified material ingot is formed in the radial direction. When the molten material is gradually cooled, compositional fluctuations occur along the growth axis of the ingot. There is a problem in that even if the material whose composition has been varied is heated to the solidus temperature and recrystallized, the non-uniformity of the composition is not corrected.

The present invention solves the above-mentioned problems, and even when impurities that do not cause compositional fluctuations and are highly segregated to the crystal forming material are added, they are added at a uniform concentration within the formed crystal. The purpose of this invention is to provide a method for manufacturing compound semiconductor crystals.

[Means for solving problems]

The method for manufacturing a compound semiconductor crystal of the present invention includes preparing an ampoule containing a compound semiconductor crystal forming material in a temperature range above the liquid phase temperature of the forming material and below a solid phase temperature range of the forming material. After inserting it into a heating furnace and melting the material in the ampoule in a temperature range above the liquidus temperature, the formed melt is transferred in the ampoule to a low temperature range below the solidus temperature range. After being dropped and solidified, the solidified forming material is recrystallized in a temperature range below the solidus temperature.

[Effect]

The method for manufacturing a compound semiconductor crystal of the present invention combines the above-described recrystallization method and zone melting method, melts the material for forming the compound semiconductor crystal, and then rapidly solidifies it to form an alloy with a uniform composition in the direction of the growth axis. Then, this alloy is melted from one end by the zone melting method, and the formed melt is dropped into an area lower than the solidus temperature to rapidly solidify it, and then left just below the solidus temperature for a long time. recrystallize,
By making it a single crystal, compositional fluctuations do not occur, and impurities with a large segregation coefficient can be added uniformly.

〔Example〕

FIG. 1(a) is an explanatory diagram showing one embodiment of the method for manufacturing a compound semiconductor crystal of the present invention, and FIG. 1(a) shows a temperature distribution diagram of a heating furnace used in the method of the present invention.

As shown in FIG. 1(a) and the first report, an alloy ingot 22 formed by rapid solidification is placed in the upper part of a quartz ampoule 21 with a sharp tip. is inserted into the heating furnace 23.

This alloy ingot is formed using mercury, cadmium,
After separately weighing and filling the ampoule with tellurium, the inside of the ampoule 21 is evacuated and one end thereof is sealed.

Here, mercury, cadmium, and tellurium are each FIG+
-xCdxTe, weigh so that x = 0.2.

The ampoule 21 was then inserted into a rocking furnace (not shown) and the rocking furnace was set at a temperature of 830°C.
By vibrating like a see-saw for 0 hours, the crystal material in the ampoule 21 is mixed and melted sufficiently uniformly.

Next, this ampoule 21 is stood vertically, and high pressure air is blown from the surrounding area to rapidly cool and solidify the melted crystal forming material. By this rapid cooling and solidification, an alloy ingot 22 of a crystal-forming material that does not cause compositional fluctuation in the tube axis direction of the ampoule 21 is formed.

Here, as shown in FIG. 1(a), the lower end portion 22A of the alloy ingot 22 is at the solidus temperature Ts (
706° C.) or lower in the heating furnace 23, and the lower end 21A of the ampoule 21 is located at a point Q in the heating furnace 23 where the temperature is lower than the solidus temperature Ts. Set up.

After installing the ampoule 21 in the heating furnace 23,
When the temperature of is between point P and point Q, the liquidus temperature TL (796℃
), and the temperature is raised so as to follow the temperature distribution curve 24 in Figure 2 of the first test).

Next, as shown in FIG. 2(a), the ampoule 21 was
It is lowered along the direction of arrow B at a speed of hr.

In this way, the alloy ingot 22 in the ampoule 21 is sequentially melted upward from its lower end 22A, and droplets 25 of the melted alloy ingot 22 are formed.
drops toward the bottom of the ampoule 21 and solidifies at the bottom 21A of the ampoule 21, and solidified crystals are formed toward the top.

After continuing this state, the lowering of the ampoule 21 is stopped when the upper end 21B of the ampoule 21 reaches the position of point Q, and the entire ampoule 21 is at a temperature just below the solidus temperature Ts (solidus The temperature of the heating furnace 24 is adjusted so that the temperature is about 10° C. lower than the crystallization temperature Ts, and the temperature is maintained in that state for about 30 days for recrystallization.

According to the method of the present invention, the formed Hg+-
xCd) In the cTe single crystal, a compound semiconductor crystal having a uniform composition with an X value of 0.2±0.02 along the growth axis direction and the radial direction of the single crystal was obtained.

Furthermore, according to the method of the present invention, As, gold (Au), and iron (F), which have large segregation coefficients for Hg+-xcdXTe crystals,
The state in which impurities such as e) and sb were uniformly added was confirmed by measuring the carrier concentration of the crystal along the growth axis direction and the radial direction.

〔Effect of the invention〕

As described above, according to the method of the present invention, a compound semiconductor crystal having a uniform composition in the growth axis direction and the radial direction of the single crystal to be formed can be formed, which is different from conventional compound semiconductor crystals. Impurity atoms such as As, which could not be added to the crystal due to large segregation, can be added uniformly, and if a semiconductor device such as an infrared sensing device is formed using the single crystal formed by the method of the present invention, This has the effect of making it possible to form a high-performance semiconductor device.

[Brief explanation of drawings]

FIG. 1(a) is an explanatory diagram of one embodiment of the method of the present invention.
Figure 2 shows the temperature distribution curve of the heating furnace used in the method of this invention; Figure 2 (a) shows the single crystal formation process diagram in the method of the present invention; The temperature distribution curve of the heating furnace, FIGS. 3 and 4 are explanatory diagrams of the conventional method. In the figure, 21 is an ampoule, 21A is the lower end of the ampoule, 21B is the upper end of the ampoule, and 22 is an ampoule. Alloy ingot, 22A is the lower end of the alloy ingot, Ts is the solidus temperature, TL is the liquidus temperature, P and Q are the positions of the heating furnace. ) Figure 2 (Q) Figure 2 tbJ Figure 3 ftB - Explanation of poppies U Figure 4

Claims (1)

[Claims] An ampoule (21) enclosing a compound semiconductor crystal forming material (22) is placed in a temperature range above the liquid phase temperature of the forming material (22) and below a solid phase temperature range of the forming material (22). After the material in the ampoule (21) is melted in a temperature range equal to or higher than the liquidus temperature, the formed melt is solidified in the ampoule. 1. A method for producing a compound semiconductor crystal, which comprises dropping the material dropwise into a low temperature range below a temperature range to solidify it, and then recrystallizing the solidified forming material in a temperature range below a solidus temperature.