Preparation of CdTe thin film by electrodeposition in butyl methyl imidazolium bath at 80 °C

CdTe thin films have been prepared on FTO substrates by eletrochemical deposition in a butyl methyl imidazolium chloride bath at 80 degrees C potentiostatically at three different applied potentials. The electrodeposition process ensures the underpotential deposition of Cd on Te coated FTO substrate. CdTe thin film was grown at a relatively higher growth rate which resulted a typical thickness of 2.7 mu m for a deposition time of 1 h at an applied deposition potential of -1.45 V. The XRD pattern indicates the formation of cubic CdTe phase with zincblende structure. The Cd to Te ratio of the film can be nicely tuned in the range of 0.8-2.27 by the selection of deposition potential. The film deposited at a potential of perfect stoichiometry (-1.45 V) shows interconnected clusters with an average size in the range of 40-100 nm. The formation of CdTe cubic phase is also ascertained by the microdomain Raman analysis. Hot probe analysis indicates the P-type behavior of the CdTe film. The band gap energy of the CdTe film is found as 1.44 eV from the UV-Vis measurements. A photoelectrochemical cell with the configuration: CdTe (0.5 cm(2)) thin film vertical bar 0.1 M K2Sx(pH-9.2) vertical bar Pt (2 cm(2)) has been constructed with the electrochemically deposited CdTe thin film. The photocurrent measurement under chopped light illumination shows an onset potential of 1 V (w.r.t. satd. Calomel) for cathodic photocurrent. The onset potential for the cathodic photo current generation has been complemented by the flat band potential of 0.93 V (w.r.t. satd. Calomel) from the Mott Schottky measurement in the same electrolyte. (C) 2013 Elsevier B.V. All rights reserved.