Preparation and Characterization of Aluminium-doped SnS Thin Films

Metallic-doping chalcogenide compounds have attracted significant interest in application of photovoltaic devices recently. In this article, Al-doped SnS films with a thickness of about 500 nm have been deposited on glass substrates by thermal evaporation technique. Al-doping concentration (from 0 at. % to 15 at.%) in the SnS films can be controlled accurately by varying Al layer thickness. The effects of Al-doping on the physical properties of the films have been investigated by X-ray diffraction, scanning electron microscopy, ultraviolet-visible-near infrared spectroscopy measurements and Hall effect measurement system. All the films are orthorhombic SnS with preferred (1 1 1) crystallites orientation, and they are of p-type conductivity. With the increasing of Al-doping concentration, the evaluated direct band gap E-dir of the SnS: Al films decreases from 1.50eV to 1.29eV and the conductivities of the films increase. Therefore, the optical and semiconducting properties of the SnS films have been improved by Al-doping.