Deposition rate dependant formation and properties of Sn2S3 and SnS thin films by co-evaporation

We report the effect of deposition rate on the formation and properties of tin sulfide (Sn2S3 and SnS) thin films prepared by co-evaporation technique. The structural, morphological and optical properties of these films have been investigated as the function of deposition rate. X-ray photoelectron spectroscopy analysis confirmed the transformation of Sn2S3 phase to SnS phase with the increase in deposition rate of tin. The structural analysis by XRD and Raman showed the formation of Sn2S3 and SnS phases. The variation in surface morphology and roughness of the as-deposited films have been examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). UV-Vis-NIR spectrometer was employed to record the transmission spectra of the samples in the wavelength range of 200-3000 nm. Film thickness (d), optical band gap (E-g), refractive index (n) and extinction coefficient (k) of the deposited thin films are estimated from the optical data. Photo conductivity of the as-deposited films has been studied using two probe method. Hall effect measurements show an n-type to p-type conversion in electrical conductivity with increase in deposition rate.