Facile synthesis and characterization of Cu₂Se thin films and self-powered p-Cu₂Se/n-Si heterojunction with high-performance photoresponse

Abstract

A facile, cost-effective, and scalable chemical vapor deposition technique was used to synthesize p-type Cu2Se thin films on glass and n-type Si substrates. Thorough characterization confirmed the films’ β-phase structure with the correct stoichiometric ratio and exceptional crystalline quality, exhibiting behavior akin to a degenerate semiconductor. Measurements unveiled a work function of 4.83 eV and a bandgap of 2.13 eV for Cu2Se. The fabrication of a p-Cu2Se/n-Si heterojunction was achieved by depositing the p-type Cu2Se thin film onto the n-type Si substrate. The resulting heterostructure displayed rectification behavior, and its energy band diagram resembled a Schottky diode. Further exploration into its photoelectric properties showcased the p-Cu2Se/n-Si heterostructure’s favorable self-powered attribute, characterized by fast, steady, reproducible, sensitive, and robust photoresponsive performance. Consequently, it proves highly suitable for applications in high-frequency photodetectors. Additionally, the p-Cu2Se/n-Si heterojunction’s photovoltaic power conversion efficiency exceeded the reported values of the CuO/Si and Cu2O/Si systems. Here, this study contributes significantly to the pivotal evaluation of p-Cu2Se/n-Si heterostructures for promising optoelectronic applications.