STRUCTURE AND OPTICAL PROPERTIES OF CdSe THIN FILMS AS A FUNCTION OF THE ANNEALING TIME

Abstract

Cadmium (Cd) and selenide powder used to prepared cadmium selenide alloy. (CdSe) thin films of thickness 1320 Å were thermally evaporated technique deposited on glass substrate at room temperature. The as-deposited films were annealed in air atmosphere at 100oC, for three different annealing times (60, 120 and 180 minutes). The structural investigation performed by x-ray diffraction (XRD) technique; showed that the films have a polycrystalline and hexagonal (wurtzite) structure. For all deposited films the preferential orientation is (002).The value of lattice constant (a), grain size, strain and dislocation density of the deposited films are calculated and their variations with annealing times are studied. The absorbance spectra of cadmium selenide thin films were recorded in the wave length range of 400 nm to 900 nm. The values of the optical band gap energy, Eg (allowed direct transitions), calculated from the absorption spectra, ranged between (2.54 and 2.41) eV