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Concentration dependant structural and optical properties of spray deposited CdTe thin films

C.H.Bhosale, D.M.Sapkal, V.M.Nikale, S.S.Shinde

Thin films of Cadmium Telluride have been deposited for various solution concentrations using a spray pyrolysis technique. The preparative parameters such as solution concentration, substrate temperature, quantity and pH of solution have been optimized using photoelectrochemical (PEC) technique. The PEC measurements show that both short circuit current (Isc) and open circuit voltage (Voc) are at their optimum values for the solution concentration of 10 mM at the optimized substrate temperature of 250°C. Further, the films have been characterized using X-ray diffraction (XRD), optical absorption, scanning electron microscopy (SEM), and energy dispersive analysis by X- ray (EDAX) techniques. XRD shows that the films are polycrystalline with cubic structure. The film deposited at optimized solution concentration has thewell-formed grains as evidenced fromSEM. EDAX analysis reveals thatmaterial formed is almost stoichiometric slightly rich in tellurium. The optical absorption studies confirm the existence of direct interband transition in CdTe with gap energy of 1.5 eV and absorption coefficient of the order of 104 cm-1.