Controlled growth of CdTe films by periodic voltammetry for solar cell applications

In the present investigation, polycrystalline n-CdTe films have been synthesized on SnO2-coated glass substrate employing voltammetric technique under periodic cycles. Optical properties of the CdTe films were investigated and the band gap energy was found to lie within the range of 1.32-1.40 eV depending on the composition of the film matrix, as obtained by EDAX analysis. The films were subjected to SEM and AFM analyses in order to study the surface morphology, topographic structure of the semiconductor surface. X-ray diffraction studies indicated polycrystalline nature of deposits containing hexagonal and cubic phases of CdTe. The stability of the films was determined through anodic polarization studies using Tafel analysis. The amount of Cd2+ dissolved during polarization was estimated by anodic stripping voltammetry. The Nyquist and Mott-Schottky plots derived from impedance spectroscopic measurements provided important information regarding electrical and semiconducting properties of the films. Cyclic voltammetry was found to be an effective method for developing potential thin films of CdTe, demonstrating photo-conversion efficiency up to the order of ∼4%.