Analysis of PV deposited ZnTe thin films through Urbach tail and photoluminescence spectroscopy

ZnTe thin films have been grown by thermal evaporation on glass substrates at room temperature at a residual pressure about 10⁻⁶ Torr and characterized for their structural and optical properties. Crystallite size and strain have been estimated from X-ray diffractogram by William – Hall method. Urbach tail, which originates near band edge due to structural disorder, has been evaluated along with optical bad gap from the absorbance spectra. Photoluminescence spectra has been recorded to get information on various excited levels. Correlation between optical absorbance and photoluminescence spectra has been established with Roosbroeck–Shockley relation. Finally effect of annealing on structural and optical properties along with photoluminescence spectra has been studied in detail.