Effects of annealing on crystallization process in amorphous Ge5Se95-xTex thin films

Amorphous Ge5Se95-xTex (where x=0, 2, 5 and 10) thin films deposited by thermal evaporation were annealed at different temperatures below their crystallization temperatures for 2 h. The optical band gap has been studied of as-deposited and annealed films as a function of photon energy in the wave length range (400-900 nm). It has been found that the optical band gap increases with increasing annealing temperatures and on Te concentration in the present system. For as-deposited films: it has been found that refractive index (n) and the extinction coefficient (k) increases on incorporation of tellurium in Ge-Se system