The Effect of Changing the Vapor Flux on Physical Properties of Nanocrystaline CdTe Thin Film, Prepared by Thermal Evaporation Method

摘要

In the present investigation, seven Cadmium Telluride (CdTe) thin films with thickness of 350nm have been prepared by vacuum thermal evaporation technique. One of them was deposited by conventional vacuum thermal evaporation technique, while six others were deposited with applying a novel vapor (low controlling system. Placing this equipment in the way of vapor flux from the source to the substrate cut the depositing flux of vapor periodically and can change the way of vapor flux. It led to considerable change of optical properties, nanocrystalline structure, and also stochiometery of the thin films. All the samples showed nanocrystalline structure. A considerable increase in absorption coefficient was observed at 520nm wavelength of light, from 5.5×10~4 cm~(-1) for the sample prepared with conventional vacuum thermal evaporation technique to 9.8×10~4 cm~(-1) for a sample which prepared by applying mentioned equipment. The most considerable change in the bandgap, grain size and Te/Cd ratio were 1.54 eV to 1.66 eV, 40nm to 15nm, and 56/44 to 60/40 respectively. The optical parameters such as absorption coefficient, bandgap, refractive index, and structural parameters such as texture coefficient, preferential orientation factor and crystallite size of samples were obtained. Also ED AX and FESEM result of samples were compared with each other in this study.