Double Pulse Electrodeposition of Cu-Ga Precursor Layer for CuGaS2 Solar Energy Thin Film

Abstract

A novel technique for synthesis of CuGaS2 solar energy thin film is presented. It is associated with double pulse electrodeposition of Cu-Ga precursor layer followed by thermal annealing treatment in sulfur atmosphere. The influence of several flexible parameters including pulse deposition potential and agitation rate on the compositions, crystal structure and morphology of the films were investigated. A relative negative shift of the higher pulse deposition potential results in the increasement of Ga content. A higher agitation rate results in higher Cu/Ga ratio and the emergence of CuS secondary phase after annealing in sulfur atmosphere. The crystal size increases with decreasing the higher pulse deposition potential. Several characterization methods including X-ray diffraction (XRD), scanning electron microscope (SEM), energy diffraction spectrum (EDS), ultraviolet–visible (UV–vis) spectra, impedance spectroscopy, and Raman spectrum are used to characterize the synthesized CuGaS2 polycrystalline thin films. Based on the experimental results, a probable formation mechanism of the CuGaS2 thin films was proposed and briefly discussed.