Temperature-Time profile effects on evolution of physical and electronic properties in visible light Cu2CoSnS4 photodetectors

Abstract

Earth-abundant quaternary chalcogenide Cu2CoSnS4 (CCTS) films on soda-lime glass (SLG) substrates are pre-pared via non-vacuum, cost-effective direct solution spin coating technique. The phase formation mechanism of CCTS films is investigated via TGA, FTIR, XRD, and RAMAN characterization. Annealing temperature effects on the crystalline phase, chemical composition, and grain growth, strongly linked with electrical and photodetection parameters of CCTS films, are systematically investigated through XRD, Raman, FEG-SEM, and EDS analysis. Through the transfer length measurement (TLM) method, the electrical properties of CCTS films annealed at 575 degrees C exhibit noticeable 92% reduction of both contact resistance (R-c) and resistivity (rho), compared to those of the film processed at 300 degrees C. The highest photoresponsivity (7.50 A/W) and specific detectivity (4.70 x 1010 Jones) of CCTS devices have been demonstrated with annealing conditions at 575 degrees C and a bias voltage of 10 V as well. The present study reveals the impact of both annealing temperature and bias voltage on photodetector performance.