Effect of Sb incorporation on the structural, optical, morphological and electrical properties of CdSe thin films deposited by electron beam evaporation technique

Abstract

Cadmium Selenide (CdSe) and antimony (Sb) incorporated CdSe (CdSe:Sb) thin films were deposited by electron beam evaporation technique at various concentration of Sb (5 wt%, 10 wt%, 15 wt% and 20 wt%). The effect of Sb concentration on the properties of CdSe thin films was investigated. Formation of hexagonal crystal structure with preferred growth along [001] direction was confirmed by X-ray diffraction analysis. The interplanar spacing, lattice constant, average crystallite size, strain and dislocation density of CdSe and CdSe:Sb thin films were calculated from X-ray diffraction studies. The crystallite size of CdSe thin film is 40 nm, which is decreased to ~25 nm with increasing Sb concentration in CdSe from 5 wt% to 20 wt% in the source material. Optical transmittance of the CdSe films obtained from UV–Vis spectra is decreased with various amount of Sb incorporation in CdSe film. Direct optical band gap of the film varies in the range of 1.74–2.3 eV as a function of Sb concentration in the source material. Photoluminescence spectra of CdSe:Sb films show near band edge emission at 605 nm and deep trap related emission band at 743 nm. The intensity of the emission bands varies and shows shifts towards the lower wavelength side with increase in Sb concentration. The electrical resistivity is relatively minimum for CdSe:Sb (5 wt%) and further increase in Sb concentration increases the resistivity of the CdSe films.