Pulsed electrodeposition of CdTe thin films: effect of pulse parameters over structure, stoichiometry and optical absorption

CdTe thin films were electrochemically deposited using unipolar current pulses of high magnitude between 2.5 and 30 mA/cm2 in an aqueous solution. Parametric study of the effect of periodic current pulse magnitude, average current and ON and OFF duration was undertaken to understand the effect of pulse variables on CdTe film properties. Increasing pulse deposition current modifies crystalline growth phase from single cubic to mixed cubic and hexagonal growth phases. In addition to the modification in CdTe growth phases, there is an increasing tendency of the oxide formation particularly CdTeO3. Increase in pulse current density or average current yields Cd rich CdTe films. The optical absorption coefficient decreases with the decrease in pulse current density, whereas an increase is observed as the OFF time decreases. The optical energy gap is found to increase with OFF time. A systematic study on the effect of pulse variables over the structure, compositional and optical properties of CdTe film is described.