Characterization of spray deposited CdTe films grown under different ambient conditions

CdTe thin film samples are prepared by spray pyrolysis under different ambient conditions and are characterized using X-ray diffraction, X-ray photoelectron spectroscopy, optical transmission and Raman scattering studies. Because of the oxidizable nature of Cd and Te ions, the oxygen content of the spray ambient is seen to affect the thin film properties by creating oxides in the film during deposition. By adjusting the amount of oxygen in the spray ambient using suitable attachments to the spray chamber, the possibility of the Cd and Te ions to react with the available oxygen in the spray ambient to form the oxides is controlled. To confirm the role of spray ambient, samples have been prepared over a range of ambient conditions that resulted in the formation of CdTe films with and without oxide phases. A gradual changeover in the chemical environment of the Te ion from Te⁴⁺ state to Te²⁻ state has been observed in the films by suitably changing the spray ambient.