Synthesis of a Cu₂SnS₃ ternary compound by thermal annealing of a metal layer in sulfur vapor

Abstract

A method for forming thin films of the Cu2SnS3 compound homogeneous in phase composition for use in solar cell devices is proposed. The Cu-Sn alloy layers deposited by thermal spraying in vacuum were annealed in sulfur vapor in a graphite chamber of the quasi-closed volume type. Using X-ray phase analysis, the optimal conditions for the formation of Cu2SnS3 films homogeneous in phase composition were found: annealing temperature 450 °C, sulfur vapor pressure ∼ 0.2 torr. The sulfide layers obtained in this way in their elemental composition correspond to the Cu2SnS3 compound stoichiometry. Cu2SnS3 films have an optical band gap of 1 eV, and the absorption coefficient in the visible region of the spectrum is 2·105 cm –1.

HETEROJUNCTION p-Cu2SnS3/n-ZnO

“…At the first stage, a 0.3 μm layer of a metal precursor was formed by thermal spraying from an alloy of copper and tin with atomic ratio Cu:Sn = 1.8. Then, the substrate with the metal layer was annealed in sulfur vapor according to the "hot wall" method in a quasi-closed chamber made from graphite [6,7] at a substrate temperature of 420 °C during 60 minutes. The vapor pressure of sulfur was set by the temperature of the sulfur source and was 20 Pa.…”