Improved optical properties of CuInSe2 thin films prepared by alternate-feeding physical vapor deposition

Abstract

High optical-quality polycrystalline and epitaxial CuInSe2 thin films were grown by a simultaneous-feeding or alternate-feeding physical vapor deposition method. The existence of the liquid-phase Cu2−xSe during the growth was confirmed in terms of meltback of the substrate. The grown films exhibited predominant near-band-edge photoluminescence peaks from 2 K up to room temperature. A clear free exciton absorption peak was observed and its full width at half maximum decreased with decreasing repetition periods of the metal feeding cycle. This result demonstrates the importance of stabilized CuInSe2 solute and Cu2−xSe solvent concentrations to obtain improved film quality and homogeneity.