The structure and properties of SnS thin films prepared by pulse electro-deposition

Abstract

SnS films were prepared onto the ITO-coated glass substrates by pulse-form electro-deposition. The potential applied to the substrates was of pulse-form and its “on” potential, V on was − 0.75 V (vs. SCE )and “off ” potential, V off was varied in the range of − 0.1–0.5 V. The SnS films deposited at different V off values were characterized by XRD, EDX, SEM and optical measurements. It shows that all the films are polycrystalline orthorhombic SnS with grain sizes of 21.54–26.93 nm and lattice dimensions of a = 0.4426–0.4431 nm, b = 1.1124–1.1134 nm and c = 0.3970–0.3973 nm, though the V off has some influence on the surface morphology of the films and Sn/S ratio. When V off = 0.1–0.3 V, the SnS films have the best uniformity, density and adhesion, and the Sn/S ratio is close to 1/1. The direct band gap of the films was estimated to be between 1.23 and 1.33 eV with standard deviation within ± 0.03 eV, which is close to the theoretical value. The SnS films exhibit p-type or n-type conductivity and their resistivity was measured to be 16.8–43.1 Ω cm.