Physical properties of highly crystalline CIS layer prepared using single phase electrodeposition and low temperature RTP annealing

Abstract

CuInSe2 nanoparticles (CIS-NP) were synthesized on ITO-coated glass substrate by electrodeposition and rapid thermal processing (RTP). The as-deposited films were annealed under argon atmosphere at 250 °C, 350 °C and 450 °C using RTP during a short annealing time. The latter is practicable to avoid further losing of the Se content in CIS films. In order to analyze the effect of annealing temperature, the structural, morphological, optical and electrical properties were investigated by means of X-ray diffraction, scanning electron microscopy, UV–Visible Spectroscopy and Mott-Schottky plots respectively. XRD results show that elaborated films have a tetragonal chalcopyrite CIS with preferential orientation along the (112) orientation. The phase formation of CIS-NP with good crystallinity was observed at low annealing temperature. Optical absorption studies indicate a direct band gap around 1.02 eV at 250 °C. The optical constants such as refractive index n(λ) and extinction coefficient k(λ) were estimated using an appropriate optical model. To determine the doping type of elaborated semiconductor, its flat band potential and the free carrier concentration we used the Mott-Schottky plots. A new attempt to anneal the electrodeposited CIS films by short annealing duration using RTP process was proved to be a useful method to synthesize polycrystalline CIS films for solar cell application.