Investigation of the effect of CdCl2 processing on vacuum deposited CdS/CdTe thin film solar cells by DLTS Original Research Article

Thin film CdS/CdTe solar cells have been prepared by conventional vacuum deposition technique. Deep level transient spectroscopy (DLTS), temperature and frequency dependent capacitance–voltage (C–V) measurements were utilised to investigate the performance limiting defect states in the CdTe layer subjected to the post deposition treatments such as CdCl2-dipping and/or annealing in air. Five hole traps, all of which have been previously reported in the literature, were identified in as-grown CdTe at 0.19, 0.20, 0.22, 0.30 and 0.40 eV above the valence band. A single hole trap level has been evidenced at 0.45 eV after both post deposition heat and CdCl2 treatments.