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

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 Omega cm. (c) 2006 Elsevier B.V. All rights reserved.