Influence of composition and heat treatment on the structure of Se-Te films

Thin films of Se1-xTex (composition x = 0, 0.2, 0.4, 0.6 and 0.8) were obtained by direct thermal evaporation of the bulk compounds. X-ray diffraction and electron diffraction microscopy investigations were carried out on Se1-xTex films. From X-ray analysis and electron diffraction measurements it was found that the films with x < 0.6 were amorphous at room temperature and when heat treated at 100 degrees C, the films became crystalline, the degree of crystallinity increasing with increased annealing temperature. For x > 0.6 the as-deposited films were crystalline and the crystallinity increased with increasing Te content. It has been reported that the binary system Se1-xTex has a hexagonal structure. The lattice parameters a and c and the grain size for the annealed films of Se1-xTex are calculated.