JPH01201094A - Method for liquid-phase epitaxial growth - Google Patents

Abstract

PURPOSE:To easily laminate and form an epitaxial crystal having multi-layer structure, without using complicated operation and causing breakage of an ampule, by clamping a substrate for epitaxial growth and a dummy substrate with a supporting member in a relatively staggered state, sealing the substrates together with a material for epitaxial growth into an ampule and performing the growth of epitaxial layer while rotating the ampule in prescribed manner. CONSTITUTION:A substrate 24 for epitaxial growth is placed on a supporting plate 23 made of quartz and is put into an upper groove 22 formed on the opposite faces of a pair of cylindrical supporting members 21A, 21B made of quartz. A lower groove 26 is formed under the substrate 24 at a position laterally staggered relative to the center axis 25 of the supporting members 21A, 21B to prevent the leak of the melt. A supporting plate 28 is stacked on a dummy substrate 27 and is inserted into and clamped with the lower grooves 26. The stacked plate 28 is sealed together with a material 29 for epitaxial growth into an ampule 30. The material 29 is melted, the ampule 30 is rotated to contact the melt 29 with the substrate 24, the temperature is lowered to form the 1st epitaxial layer, the ampule 30 is rotated to contact the residual melt 29 with the dummy substrate 27 to deposit a dummy layer and the ampule is rotated to contact the melt again with the substrate 24 to form the 2nd epitaxial layer having different composition.

Description

[Detailed Description of the Invention] [(Already Required)] Concerning a tilted liquid phase epitaxial growth method, epitaxial layers of mercury, cadmium, and tellurium with different compositions can be continuously grown on a substrate without breaking the ampoule using the same epitaxial growth melt. The epitaxial growth substrate and the dummy substrate were shifted in the vertical direction and relative to the central axis of the support member that sandwiched the growth substrate and the dummy substrate. After melting the epitaxial growth material, the ampoule is rotated to bring the molten melt into contact with the substrate, and while the temperature of the melt is lowered, the first After forming the epitaxial layer of the first epitaxial layer on the substrate, the ampoule is rotated to bring the dummy substrate into contact with the melt after the first epitaxial layer has been deposited, and while lowering the temperature of the melt, the composition of the first N crystal layer is changed. Different dummy layers are deposited on the dummy substrate, then the ampoule is rotated, the epitaxial growth substrate is brought into contact with the melt after the dummy layer has been deposited, and the first epitaxial layer is deposited on the substrate while lowering the temperature of the melt. It is constructed by forming a second epitaxial layer having a different composition.

[Industrial application field]

The present invention relates to a liquid phase epitaxial growth method, particularly mercury, cadmium, tellurium (Hgl-) containing easily evaporable mercury.
The present invention relates to a tilted liquid phase epitaxial growth method for forming a crystal layer of (xCdxTe) on a substrate in a multilayer structure with varying composition.

Photoelectric conversion elements such as infrared sensing elements use l1g, -eCd, and Te crystals, which have narrow energy band gaps. When such a crystal of 11g, □CdXTe is epitaxially grown on a cadmium telluride (CdTe) substrate, mercury is an easily evaporable element, so
Using an ampoule with a sealed structure to prevent evaporation of mercury, the molten Hg1-XCdXTe is brought into contact with the substrate.
, A tilted liquid phase epitaxial method for growing an epitaxial layer of Te is widely used because the apparatus is simple and the composition of the epitaxial layer can be easily controlled.

By the way, as a material for forming an infrared sensing element, for example, Hg+-x Cdx Te with an X value of 0.2 is used on a CdTe substrate.
There is a demand for materials that can form epitaxial layers as thin as about 10 μm, and such thin layers of H81~, Cd
.

To form a thin Te epitaxial layer, direct Cd
When an epitaxial layer is formed on a Te substrate, interdiffusion occurs between the atoms constituting each substrate and the epitaxial layer between the epitaxial layer and the substrate, making it impossible to obtain an epitaxial layer with a desired composition.

Therefore, H with an X value of 0.25 is placed on the CdTe substrate in advance.
g1□After forming a thick epitaxial layer of Cd and Te to a thickness of about 20 μm as a buffer layer,
118. with a value of 0.2. □An epitaxial layer of Cd and Te is formed thinly to a thickness of 10 μm.

[Conventional technology]

Conventionally, Hg+-x Cdx Te with such a multilayer structure
When forming an epitaxial layer on a CdTe substrate, as shown in FIG. 6, a CdTeg plate 3 to be epitaxially grown and a support plate 4 are inserted in a groove 2 of a cylindrical support member 1 made of quartz in an overlapping manner. Along with Hg1-x CdxT
After inserting the epitaxial growth melt forming material 5 consisting of e into the ampoule 6, the ampoule 6 is evacuated, and one end A of the ampoule is sealed by melting.

Next, after melting the melt-forming material 5, the ampoule 6 is
is rotated 180 degrees in the direction of arrow B, the melt is brought into contact with the substrate, the temperature of the melt is lowered, and as shown in FIG.
．． A first layer of 25 epitaxial layers N7 is formed.

Then, after breaking the ampoule 6 and taking out the substrate 3 on which the first epitaxial layer 7 was formed, a material for forming Ilg,-,CdXTe with an X value of 0.20 and the first layer were placed in a separate ampoule. After encapsulating the substrate 3 on which the epitaxial layer has been formed, the above-described operations are repeated to form a second epitaxial layer of crystals of Ig+-7Cd and Te with an X value of 0.20 on the substrate 3. It is formed as 8.

[Problem to be solved by the invention]

However, in the above method, after forming the first epitaxial layer 7 on the substrate 3, the ampoule 6 must be broken and the material for forming the second epitaxial layer must be sealed in a separate ampoule. It was complicated and the ampoule had to be broken, so the ampoule was consumed quickly.

Furthermore, it is necessary to take out the substrate 3 on which the 1N epitaxial layer 7 is formed from the ampoule 6, and at that time, the first epitaxial layer 7 is exposed to the atmosphere. Furthermore, if the second epitaxial layer 8 is formed thereon, there is a problem that the crystal interface between the first epitaxial layer 7 and the second epitaxial layer 8 is oxidized by moisture in the atmosphere and contaminated.

The present invention eliminates the above-mentioned problems and allows epitaxial crystals of different compositions to be successively deposited on a substrate by a simple method without breaking the ampoule, and without requiring the troublesome work of refilling the epitaxial layer forming material. The purpose of this invention is to provide a phase epitaxial growth method.

[Means to solve the problem]

In the epitaxial growth method of the present invention, an epitaxial growth substrate and a dummy substrate are sandwiched between the support members while vertically shifting the growth substrate and the dummy substrate relative to the center axis of the support member. The epitaxial growth material is sealed in an ampoule together with an epitaxial growth material, and after melting the epitaxial growth material, the ampoule is rotated to bring the melted melt into contact with the substrate, and the first epitaxial layer is deposited on the substrate while lowering the temperature of the melt. After forming the crystal layer on top, the ampoule is rotated to bring a dummy substrate into contact with the melt after the first epitaxial layer has been deposited, and while lowering the temperature of the melt, a dummy layer having a composition different from that of the first crystal layer is added to the dummy substrate. The ampoule is then rotated to bring the epitaxial growth substrate into contact with the melt after the dummy layer has been deposited, and while lowering the temperature of the melt, a second epitaxial layer having a different composition from the first epitaxial layer is deposited on the substrate. It is constructed by forming two epitaxial layers.

[For production]

Hg+-x Cds on the CdTe 3 substrate described above.
When epitaxially growing a crystal of Ilg, -, Cd, ITe from a Te melt, the segregation coefficient of Cd is )Ig
Because it is larger than the segregation coefficient of Hg+-x Cdx
As the Te layer is formed, the Cd/Hg ratio in the melt becomes smaller.

In other words, as a CdTe substrate is brought into contact with a melt of Hg+-Cd, Te and an epitaxial layer is grown on the substrate while lowering the temperature of the melt, an epitaxial layer with a small X value is formed on the surface of the epitaxial layer. Ru.

This state is shown in FIG. In the figure, the vertical axis shows the X value, and the horizontal axis shows the thickness of the epitaxial layer (μm) and the temperature of the melt (°C).

As described above, as the formed epitaxial layer grows, the X value decreases as shown by the straight line 11.

The method of the present invention provides Cd0X on a substrate for epitaxial growth.
After growing an epitaxial layer with a value of 0.25,
The X value of the epitaxial crystal to be formed is 0.25 to 0.
．． After pre-depositing a dummy layer on a dummy substrate, a melt in a range where the melt temperature varies up to a value of 20, that is, a melt with a melt temperature from 490°C to 475°C, is deposited on a substrate on which a first epitaxial layer is formed. By contacting the melt after the dummy layer has been deposited, a second epitaxial layer having an X value of 0.20 can be formed.

As a result, Hg, -, Cd with an X value of 0.25 are placed on the substrate.
A crystalline layer of xTe is formed as a first epitaxial layer, and tlgl-, (ca
The XTe crystal layer can be easily and continuously laminated as a second epitaxial layer without replacing the epitaxial layer forming material.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an epitaxial growth apparatus used in the method of the present invention, and FIG. 2 is a sectional view taken along line 1-1' in FIG.

As shown in FIGS. 1 and 2, CdT is installed on a support plate 23 made of quartz in an upper groove 22 provided on the opposing surfaces of support members 21A and 21B made of cylindrical quartz.
An epitaxial growth substrate 24 made of e is installed,
At the bottom of the upper groove 22, the cylindrical support member 21A is provided.
, 21B are stacked and inserted into the lower groove 26 provided at a position shifted in the lateral direction with respect to the central axis 25, with the dummy base 27 at the bottom and the support plate 28 at the top. Here, one end of the dummy substrate 27 and the support plate 28 of the dummy substrate 27 is connected to the support member 21A, in order to prevent melt from flowing out to the epitaxial growth substrate 24 side when forming a dummy layer on the dummy substrate 27. 21B
Make sure that it is located at the left end of (.

Further, the lower part of the dummy substrate 27 is filled with a melt forming material 29 made of Ig+□CdXTe, and the supporting members 21A, 21B, the epitaxial growth substrate 24,
The dummy substrate 27 is sealed with an ampoule 30.

To describe the case where the method of the present invention is carried out using such an epitaxial growth apparatus, first, FIG. 3(a)
As shown in FIG. 3, the epitaxial growth material described above is melted to form an epitaxial growth melt 29.

Next, the ampoule 30 is rotated 180 degrees along the direction of arrow C, and the epitaxial growth substrate 24 is brought into contact with the epitaxial growth melt 29 in the state shown in FIG. 5 as shown
IIg+-x with an
A crystal layer of Cd and Te is formed as a first epitaxial layer to a thickness of 20 μm.

Next, the ampoule 30 is rotated 270 degrees along the direction of the arrow, and the epitaxial growth melt 29 is brought into contact with the dummy substrate 27 in the state shown in FIG. 3(C), and the temperature of the melt is shown as the straight line 31 in FIG. As in 490°C T, U
The temperature is lowered at a predetermined temperature gradient to 475°C, and the X value is lowered from 0.25 to 0.2
A crystal layer of 'g+-x Cdx Te up to 0 is deposited as a dummy layer.

Next, the ampoule 30 is further rotated 270 degrees along the direction of arrow E, and the epitaxial growth melt 29 after the dummy layer has been deposited is brought into contact with the epitaxial growth substrate 24 in the state shown in FIG. 3(d), and the temperature of the melt is increased. straight line 3
As shown in Figure 1, the temperature is lowered to 475°C, which is the temperature of T2, with a predetermined temperature gradient, and the X value of the second layer is 0.2 on the substrate.
A crystal layer of 0 Hg+-x caX Te is formed as a second epitaxial layer to a thickness of 10 μm.

Next, the ampoule 30 is further 180 mm along the direction of arrow F.
The substrate is rotated once to remove unnecessary melt from the substrate for epitaxial growth, thereby obtaining a substrate on which epitaxial crystals of the first and second layers are formed.

According to the method of the present invention, multiple layers of epitaxial crystals can be grown at a high temperature without breaking the ampoule or contaminating the growth interface of the epitaxial layer with the atmosphere by filling the melt-forming material only once. Can be formed in a state of dignity.

〔Effect of the invention〕

As is clear from the above description, the present invention does not require complicated work and does not damage the ampoule.
It is possible to easily form a multilayered epitaxial crystal by just filling the melt-forming material for epitaxial growth in one time without exposing the interface of the epitaxial layer to the atmosphere. It is extremely effective as a

[Brief explanation of the drawing]

Figure 1 is a sectional view of the apparatus used in the method of the present invention, Figure 2 is a sectional view taken along line 1-1' in Figure 1, and Figures 3(a) to 3(e) FIG. 4 is a temperature profile diagram of the melt used in the method of the present invention; FIG. 5 is a detailed explanatory diagram of the present invention; FIG. 6 is an explanatory diagram of the conventional method; FIG. 7 is a cross-sectional view of an epitaxial crystal formed by a conventional method. In the figure, 11 is a straight line showing the relationship between the X value and the thickness of the epitaxial layer, 21A and 21B are support members, 22 is an upper groove, 23 is a support plate, 24 is an epitaxial growth substrate, 25 is a central axis, and 26 is a lower part. groove, 27 is a dummy board, 28 is a support plate,
29 is a melt-forming material, 30 is an ampoule, and 31 is a temperature profile curve of the melt.

Claims (1)

[Claims] Epitaxial growth substrate (24) and dummy substrate (2
7) supporting members (21A, 21B) that sandwich the substrate (24) and the dummy substrate (27) in the vertical direction;
The epitaxial growth material is sandwiched between the supporting members (21A, 21B) in a state in which it is shifted relative to the central axis (25) of the After melting (29), the ampoule (30) is rotated to bring the melted melt into contact with the epitaxial growth substrate (24), and the first epitaxial layer is grown on the substrate while lowering the temperature of the melt (29). After forming the first epitaxial layer, the ampoule (30) is rotated to bring the dummy substrate (27) into contact with the melt (29) after the first epitaxial layer has been deposited, and the temperature of the first epitaxial layer is lowered.
A dummy layer having a different composition from the epitaxial layer of the layer is deposited on the dummy substrate (27), and then the ampoule (30) is rotated, and the epitaxial growth substrate (24) is deposited on the melt (27) after the dummy layer has been deposited.
29) A liquid phase epitaxial growth method characterized by forming a second epitaxial layer having a composition different from the first epitaxial layer on the substrate (24) while lowering the temperature of the melt.