Annealing effect on the optical energy gap of (CdTe) thin films

Abstract

Cadmium telluride thin films deposited by Co-evaporation technique on glass substrates.UV-VIS absorption data of films grown at room substrate temperature, as well as to theannealing thin films at the temperatures (373,473,573) K.The absorption coefficient α and optical energy gap Eg of the films obtained from theabsorption data are measured in the strong absorption regime (300-1100) nm. Both theallowed direct and indirect optical transitions occur in CdTe thin films. The optical energygaps for thin films deposited at room temperature that are associated with allowed direct andindirect interband transitions are 2.75 and 1.45 eV respectively. It observed that there is anincrease in optical energy gap with increase in annealing temperatures.