Optimization of Thickness and Number of Layers for CdTe Films Deposited by Stacked Elemental Layers Method and Annealed in Different Environments

Thin films of CdTe were deposited by stacked elemental layers method on
glass substrate. The effect of different evaporation parameters upon the
structural and optical properties has been investigated by using X-ray
diffraction and optical spectrophotometry measurements. X-ray data were
collected and crystal structure analyses were performed using Rietveld
refinement method. In the present study the thickness of the films was varied in
the range 100 - 300 nm, additionally the layers were adjusted in range between
3-5 layers. Furthermore, the films were annealed at 200 oC for 30 minutes in
different environments. X-ray diffractograms showed that films annealed in
vacuum exhibit only a single CdTe phase while multiphase films were obtained
for films annealed in air. The results show that decreasing of the film thickness
and/or increasing of the number of stacked layers enhances the phase purity of
the films. Optical energy gaps (1.36 - 1.51 eV) were estimated from the
manipulation of transmission and reflection data. The analysis of structural
and optical data revealed optimum conditions for obtaining high quality films
(single phase) that the thickness is 200 nm and the number of layers is five.