Tin sulfide films by spray pyrolysis technique using L‐cysteine as a novel sulfur source

Abstract

AbstractTin sulfide films were deposited by spray pyrolysis method using aqueous solutions containing tin chloride (SnCl2) and L‐cysteine (HO2CCH(NH2)CH2SH) as a novel source of sulfur instead of commonly used thiourea. L‐cysteine prevents SnCl2 from hydrolysis due to a complex formation as confirmed by Fourier Transformed Infrared Spectroscopy studies. The solution that contained SnCl2 (Sn) and L‐cysteine (S) at molar ratios of Sn:S=1:1, 1:2 and 1:4 was sprayed onto glass substrates at varied temperatures between 200 °C and 370 °C. Films were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX) and UV‐Vis spectroscopy. Accord‐ ing to XRD, spray of the 1:1 solution results in films that are composed of SnS as a main crystalline phase. An unidentified crystalline phase was present independent of the growth temperature. Single phase SnS films with bandgap value of 1.7 eV could be grown using the 1:2 solution at deposition temperature of 370 °C. Films grown from 1:4 solutions are amorphous using deposition temperatures below 370 °C, and composed of a mixture of SnS and Sn2S3 phases when grown at 370 °C. EDX study shows that SnS films contain high amount of carbon and oxygen containing residues independent of the deposition temperature and precursors' molar ratio in the spray solution. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)