Substrate temperature influence on the optical and electrical properties of spray deposited Sn2S3 thin films

Abstract

Sn2S3 Nano crystalline thin films were deposited by spray pyrolysis technique onto glass substrates for three different temperatures 320°C, 360°C and 400°C and the effect of substrate temperature on the structural, compositional, electrical and optical properties of Sn2S3 thin film were investigated. X-ray diffraction analysis (XRD) confirmed the formation of single phase polycrystalline Sn2S3 crystals in the preferential direction (211). With increase in substrate temperature the film thickness was observed to increase and the crystals became smaller in size. SEM images confirmed a uniform, homogeneous coating of Sn2S3 thin film with needle shaped Nano crystals at 400°C. The EDX (Energy Dispersive X-ray) analysis depicted the films were non-stoichiometric due to the evaporation of sulphur at higher temperatures. From UV-Vis-NIR spectroscopy studies the absorption coefficient of the film was determined to be of the order of 104cm−1 and the refractive index and dielectric constants obtained indicated a normal dispersive film. The electrical properties were investigated by Hall measurements at room temperatures and a resistivity of the order of 10−1Ωcm and carrier concentration in the range of 1016cm−3 were observed. Sn2S3 thin films sprayed at 400°C are a potential candidate as n-type absorber layer in thin film photovoltaic cells.