Influence of deposition conditions on properties of CdTe films

The aim of this work was to synthesize the CdTe thin film electrodes and to investigate the influence of the deposition conditions on the properties of CdTe films. Two different methods of CdTe formation were used: two-step electrochemical-chemical method and one-step electrochemical method. It was found, that the properties of CdTe films differ depending strictly on the experimental conditions during deposition such as: deposition potential, bath composition, temperature. Properties like chemical composition, crystallinity, band gap energy and morphology were investigated by various techniques such as Raman and Photoelectron Spectroscopy, X-ray Diffraction, UV-vis spectrometry, Scanning Electron Microscopy and Atomic Force Microscopy. The photoactivity of as-deposited CdTe films was investigated in the electrolyte solution which should protect them against photocorrosion. The results suggested that CdTe films prepared by both methods were unstable and undergo photooxidation. Therefore, further experiments were carried out with the application of polyindole (conducting polymer) layer as a protective coating against CdTe photocorrosion. The hybrid films polyindole-CdTe (PIN-CdTe) were prepared by the electropolymerization of indole on a Pt electrode followed by the electrodeposition of CdTe. The composition of the deposits was studied by Raman spectroscopy. SEM images revealed that in such deposits, the CdTe crystallites are formed either on the polymer films or they are embedded into the polymer layer. It was shown that polyindole layer improved the photocurrent and photostability of CdTe.