The study of CdSe thin film prepared by pulsed laser deposition for CdSe/CdTe solar cell

Abstract

Over the past few years, the studies of CdS/CdTe solar cells have become the mainstream, which have achieved good performance of exceeding 20 %. Here, we prepare CdSe thin films by pulsed laser deposition (PLD) which is one of promising techniques to synthesize semiconductor thin films. In this paper, the optical and electrical properties as well as the crystal structure of CdSe thin films deposited under different temperatures are investigated. We find that the deposition rate adds firstly, and then decreases with the increase of substrate temperature. Transmittance spectrum suggests the absorption edges of CdSe thin films under the condition of high temperature move towards short wavelength. The band gaps of CdSe thin films are 1.948, 1.976, 2.013 and 1.978 eV at the deposition temperature of 150, 250, 350, 450 °C, respectively. X-ray diffraction analysis indicates the formation of cubic phase with a strong (111) preferential orientation. The surface morphology of CdSe thin film and the cross-sectional structure of CdSe/CdTe layer are also analyzed. Based on these studies, we further fabricate the CdSe (PLD)/CdTe solar cells that present excellent performance of response in the range of long wavelength over 900 nm and a good efficiency of near 10 % has been realized.