Effect of antimony dopant on structural and optical properties of CdSe thin films

CdSe:Sb thin films with a varying concentration of Sb3+ (0-5 mol%). have been deposited by employing a chemical deposition process. The composition of the as-grown samples was determined by the chemical analysis and EDS technique. The XRD analysis revealed that, the samples are polycrystalline and exhibit a hexagonal wurtzite and cubic zinc blend phase structures. The calculation of lattice parameters (a = 4.2998 Angstrom and c = 7.042 Angstrom) showed good fit with the JCPD data. The average grain size determined by FWHM method is increased up to 0.1 mol % and then decreased at higher Sb3+ doping concentration. Scanning electron micrographs showed crystalline nature with grain size increased considerably and intercrystalline spacing decreased up to 0.1 mol% Sb doping level. A considerable amount of over growth / fusing of the grains has also been detected. Optical absorption studies revealed a high absorption coefficient (10(4)-10(5) cm(-1)) with a direct type of transitions (m congruent to 0.5). The estimated band gap decreased typically from 1.79 eV to 1.61 eV as Sb 31 concentration was increased from 0 to 0.1 mol% and further, it increased on the highef doping side.