Preparation method of cadmium telluride thin film

Abstract

The invention relates to a method for preparing cadmium telluride film, which belongs to the technical field of material plating. In the method, the distance from a cadmium telluride source to a substrate in a vacuum chamber of a near space sublimation device is controlled, the oxygen content in the vacuum chamber is controlled through regulating the air pressure of the vacuum chamber, and twice growth of the same phase crystal lattice of the cadmium telluride film is formed through twice heating, heat insulation and cooling processes carried out on the cadmium telluride source and the substrate at different vacuum degrees and temperatures, so the cadmium telluride film with large crystal grains and good tissue structures are formed. In addition, the appearance relying degree of the two growth modes on the substrate is greatly reduced through being compared with that of other growth modes, so the cadmium telluride film can be directly grown on the ordinary glass at low cost and high efficiency.

Description

technical field [0001] The invention relates to a method for preparing a cadmium telluride thin film, belonging to the technical field of material plating. Background technique [0002] Cadmium telluride (CdTe) is an important material in group II-VI compounds. It has two conductivity types, n-type and p-type, and the mobility of both carriers is good. It is widely used in the preparation of electronic devices. At the same time, the CdTe film has a direct bandgap structure with an energy gap value of 1.45eV, which is just in the energy gap range of an ideal solar cell. One of the ideal solar cell materials for high efficiency. [0003] At present, there are many methods for preparing cadmium telluride thin films, such as electrochemical deposition, radio frequency sputtering, vacuum evaporation, spraying thermal decomposition, near-space sublimation, etc. The near-space sublimation method has simple equipment, and the laboratory process is easy to be extended to industrial...

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Problems solved by technology

[0004] According to the applicant's understanding, the current patent literature reports related to the preparation of cadmium telluride thin films include: 1) Chinese patent application number 200580028243.5 reports a method for coating a substrate under atmospheric pressure. The evaporated semiconductor material is condensed on the low-temperature substrate. This method only provides multiple condensations of multiple layers of semiconductor material on the substrate. It is not a method specifically for the thin preparation of cadmium telluride, and the semiconductor material layer prepared by this method does not have The characteristics of good texture and large crystal grains; 2) Chinese patent application number 200880128189.5 reports a polycrystalline electronic device, which is made of textured metals, alloys, nitrides, borides, oxides, fluorides, The cadmium telluride film with uniaxial texture, biaxial texture and triaxial texture is obtained on carbide, silicide and metal alloy substrates. Although the cadmium telluride film formed on the device has good texture and grain The size is large, but it depends on the texture of the metal substrate, and the formed polycrystalline film is prone to aging due to lattice mismatch; 3) Chinese patent application number 200880128189.5 reports a multi-stage cadmium sulfide film deposition method. The method is to deposit a multi-layer cadmium sulfide film with a chemical bath, which is completely different from the existing cadmium telluride film preparation method

[0005] In summary, in the existing CdTe film preparation technology, either only small grains but good texture CdTe films can be produced, or only large grains but poor texture CdTe films can be produced, or Depending on the highly textured substrate, or the crystal lattice of the polycrystalline film is easily mismatched and aged, it is impossible to produce a large-grained and well-textured CdTe film; Large-grain and well-textured cadmium telluride thin films are directly produced on the substrate (such as glass)

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