Zinc selenide (ZnSe) crystal is a material with excellent infrared optical properties. With a transmittance of 70% in the 0.5-22 u m band, it can be widely used in infrared optical windows, infrared optical lenses and other thermal imaging systems, and is an important infrared optical material in military and civil applications.
The melting point of zinc selenide (ZnSe) material is 1520℃, and it has a large vapor pressure at 1000℃, so it is difficult to prepare large size single crystal. At present, ZnSe polycrystals are most frequently used, and the methods usually used are hot pressing and chemical vapor deposition (CVD). The infrared transmission performance of ZnSe materials prepared by hot pressing is much inferior to that of ZnSe materials prepared by CVD, therefore, CVD has become an important method for the preparation of ZnSe polycrystals.
The preparation of ZnSe polycrystalline materials by CVD is carried out in a vacuum low-pressure confined growth furnace. The reactive gas H2Se and high temperature Zn vapor are synthesized in the deposition chamber under the transport of Ar carrier gas. The reaction equations and growth conditions are as follows:
Reaction equation:
H2Se(gas)+Zn(gas)= =ZnSe(solid)+H2 (gas )
Growth conditions:
Reaction temperature: 400-900°C
Reaction pressure: 100 -2000Pa
Generation of CVD ZnSe polycrystalline materials
