JPH0451970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to an improvement in a rotary liquid phase epitaxial growth apparatus having a closed structure.

(b) Technical background Compound semiconductor crystals containing mercury (Hg), such as mercury-cadmium-tellurium (Hg _{1-X Cd} Used as a forming material.

Liquid phase epitaxial growth is a method for forming such Hg _1-X Cd _X Te crystals in a large area and in a thin layer, convenient for device formation.

By the way, Hg is a very easily evaporable element, so
As an apparatus for forming such a crystal of Hg _1-X Cd _X Te by a liquid phase epitaxial method, the present inventors have previously proposed a rotary liquid phase epitaxial growth apparatus with a closed structure.

(c) Prior art and problems Figure 1 is a perspective view of the previously proposed liquid phase epitaxial growth apparatus, and Figure 2 is a sectional view taken along line A-A'.
FIG. 3 is a sectional view taken along line B-B'.

As shown in FIGS. 1, 2, and 3, the previously proposed liquid phase epitaxial growth apparatus has a support member 2 made of a pair of quartz rods inscribed in a sealed tube 1 made of heat-resistant quartz. It has a configuration with . A rectangular recess 3 facing each other is cut in the support member 2 at a position offset from the center thereof, and a substrate installation stand 4 made of a rectangular quartz plate is fitted into this recess. ing. The vertical dimension C of this recess is the thickness of this substrate installation stand 4 and the cadmium telluride (CdTe) installed on it.
The dimensions are equal to the sum of the thicknesses of the substrates 5.

A CdTe substrate 5 is placed on the substrate installation stand 4 of such an epitaxial growth apparatus, and a Hg _1-X Cd _X Te epitaxial layer forming material 6 to be formed on the substrate is placed at the bottom of the substrate installation stand. The epitaxial growth apparatus filled with Hg 1-X Cd X Te is inserted into a heating furnace, and the heating furnace is heated to melt the Hg _1-X Cd _X Te material.
After that, when the Hg _1-X Cd _X Te material is melted, the sealed tube 1 is rotated 180 degrees to bring the Hg _1-X Cd _X Te solution into contact with the substrate, and then the temperature of the heating furnace is lowered at a predetermined cooling rate. A crystal of Hg _1-X Cd _X Te is epitaxially grown on the substrate. After that, when the epitaxial growth reaches a predetermined thickness on the substrate, the sealed tube 1 is rotated 180° again to remove the Hg _{1-X Cd} The epitaxial layer is formed in a similar manner.

However, in the liquid phase epitaxial growth apparatus having the structure described above, the molten Hg _{1-X Cd} This has the drawback that epitaxial growth cannot be performed by supercooling at a temperature slightly lower than the melting point of the material for forming the crystal layer of Hg _1-X Cd _X Te by ΔT°C.

If an epitaxial layer is formed on a substrate in such an unbalanced state, crystal defects will occur in the formed epitaxial layer. In addition, by supercooling the growth, the interface between the substrate and the epitaxial layer on it becomes a flat interface without any unevenness, allowing a P-N junction to be formed with good reproducibility, and the epitaxial layer to be formed to be smooth. However, with conventional epitaxial growth equipment, it is difficult to maintain the solution in a supercooled state or in a saturated state.

(d) Purpose of the Invention The present invention solves the above-mentioned problems, and the material for forming the epitaxial layer to be formed on the substrate easily becomes saturated at a predetermined set temperature of the heating furnace.
An epitaxial layer can be formed on a substrate in an equilibrium state in which the concentration of the solution does not change with respect to the heating temperature, and an epitaxial layer can be grown on the substrate by supercooling at a temperature that is very slightly lower than the melting point of the solution. The object of the present invention is to provide a novel liquid phase epitaxial growth apparatus.

(e) Structure of the Invention Such an object is to provide an L-shaped board mounting base with a pair of support members inscribed in a heat-resistant sealed tube, and an end of one side of the board mounting base is connected to the inner wall of the heat-resistant sealed tube. The end of the other side is supported in the tube axis direction so as to form a minute gap with the inner wall of the heat-resistant sealed tube, and a substrate for crystal growth is placed on the surface of one side of the substrate mounting table, and a substrate for crystal growth is placed on the back side of the substrate mounting table. The thin plate for source is placed respectively, and the thin plate for source and the substrate for crystal growth are sequentially immersed in the crystal layer forming material melt filled under the crystal growth substrate. This is achieved by a liquid phase epitaxial growth apparatus characterized in that the heat-resistant sealed tube is configured to be rotatable.

(f) Embodiment of the Invention An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 4 is a perspective view of the liquid phase epitaxial growth apparatus of the present invention, FIG. 5 is a sectional view taken along the line D-D' of the perspective view, and FIGS.
FIG. 2 is a cross-sectional view taken along line -E', showing the operating state of the liquid phase epitaxial growth apparatus of the present invention.

As shown in FIGS. 4 and 5, the liquid phase epitaxial growth apparatus of the present invention includes a sealed tube 11 made of quartz or the like.
A support member 12 consisting of a pair of quartz rods inscribed in
A, 12B, CdTe substrate 13 and substrate holder 1
4 and a CdTe source thin plate 15 is provided. As shown in FIG. 6, such a substrate holding stand 14 is bent at right angles and extends downward, and its bent end has a predetermined gap l with the inner wall of the sealed tube. Therefore, the recess 16 needs to have an L-shaped groove shape that corresponds to the shape of the board mounting table 14. and CdTe
The substrate 13 and the CdTe source thin plate 15 are inserted into the recess and placed in a stacked manner with the substrate holder 14 in between. Then, after filling the Hg _{1-X Cd} Melt the Hg _1-X Cd _X Te material by increasing the temperature.

Thereafter, when the Hg _1-X Cd _X Te material is melted, the sealed tube 11 is rotated 180° in the direction of arrow G, as shown in FIG. In this way, Hg _1-X Cd _X Te solution 1
7 passes through the gap l between the inner wall of the sealed tube 11 and the end of _the substrate mounting _stand 14, and as shown in FIG.
A solution of Hg _1-X Cd _X Te is saturated with the components of the CdTe source plate.

Therefore, by setting the temperature of the heating furnace to a predetermined temperature, a solution of Hg _1-X Cd _X Te in a saturated state at that temperature can be easily obtained.

Furthermore, a supercooled solution of Hg _1-X Cd _X Te in which the temperature of the heating furnace is lowered by an extremely small temperature below the melting point of Hg _1-X Cd _X Te can be easily realized.

Next, as shown in FIG. 7, the sealed tube 11 is rotated 360° in the direction of arrow H, and the saturated Hg _{1-X Cd} solution or the supercooled state mentioned above.
After the Hg _1-X Cd _X Te solution is brought into contact with the substrate 13, the temperature of the heating furnace is lowered and the saturated Hg _{1- X Cd -X}
Equilibrium growth of Cd _X Te crystals. In addition, by contacting the substrate with a supercooled Hg _1-X Cd _X Te solution,
Hg _1-X Cd _X Te crystals can be grown by supercooling.

Thereafter, the sealed tube 11 is further rotated 180° in the direction of arrow K, so that the Hg _1-X Cd _X Te solution adhering to the substrate can be removed through the gap l.

In this way, a crystal of Hg _1-X Cd _X Te can be grown on the substrate in equilibrium and undercooled at a predetermined temperature. In this case, CdTe is added to the Hg _1-X Cd _X Te solution.
By measuring the amount that the thin sauce plate melts into
It is possible to detect the composition of the Hg _{1 - X Cd} The components of the thin plate are dissolved to saturate the solution of Hg _1-X Cd _X Te, and the solution can be used to equilibrate the epitaxial growth on the substrate. In addition, the temperature at which the saturation state described above will occur is detected in advance by the weight loss of the material of the source thin plate, and the temperature of the solution is set to a temperature slightly lower than that temperature, and a crystal layer of Hg _1-X Cd _X Te is formed on the substrate. can be grown by supercooling.

(g) Effects of the Invention As described above, if the liquid phase epitaxial growth apparatus of the present invention is used, an epitaxial layer of Hg _{1 -X Cd}
This method has the advantage that growth can be performed under stable conditions in which the Cd _X Te solution is saturated, and that a high-quality epitaxial layer can be obtained by supercooling the Hg _1-X Cd _X Te solution.

[Brief explanation of the drawing]

1 to 3 are perspective views and sectional views of a conventional liquid phase epitaxial growth apparatus, and FIGS. 4 to 8 are perspective views and sectional views of a liquid phase epitaxial growth apparatus of the present invention. It is. In the figure, 1 and 11 are sealed tubes, and 2 and 13 are CdTe
Board, 3 and 14 are board installation stands, 4 and 16 are recesses,
5, 12A, 12B are supporting members, 6, 17 are
A solution of Hg _{1-X Cd}

Claims (1)

[Claims] 1. An L-shaped board installation stand is inscribed in the heat-resistant sealed tube by a pair of support members, and the end of one side of the board installation stand is in contact with the inner wall of the heat-resistant sealed tube, and the end of the other side is in contact with the inner wall of the heat-resistant sealed tube. The tube is supported in the axial direction so as to form a minute gap with the inner wall of the sealed tube, and a substrate for crystal growth is placed on the surface of one side of the substrate mounting table, and a thin plate for source is placed on the back surface of the substrate mounting table. The heat-resistant sealed tube including the substrate mounting stand is configured to be rotatable so that the source thin plate and the crystal growth substrate are sequentially immersed in the crystal layer forming material melt filled under the growth substrate. A liquid phase epitaxial growth apparatus characterized by: