Tin sulphide thin films synthesised using a two step process

Tin sulphide (SnS) is of interest for use as an absorber layer in thin film solar cells. This is because the constituent elements, tin and sulphur, are abundant and non-toxic and the compound has a near optimum direct energy bandgap (1.35 eV) for photovoltaic solar energy conversion. This paper investigates the formation of thin films of tin sulphide on soda-lime glass substrates using a two step method. The layers are formed by sputtering tin onto glass and then annealing in a 5% H2S in argon gas environment for a temperature in the range 300-450 °C, for annealing time of 2 hours. The physical and chemical properties of the layers formed are compared to those synthesised by annealing sputtered tin layers in an environment containing elemental sulphur. The surface texture of the films formed were observed using scanning electron microscopy, the film composition determined using energy dispersive X-ray analysis and the phases present and structure of each phase using X-ray diffractometry. Reflectance versus wavelength data was also used to determine the energy bandgap.