Effects of aluminum and manganese impurity concentrations on optoelectronic properties of thin films of Tin Sulfide (SnS) using CBD method.

Abstract

Thin films of Tin Sulfide (SnS) with varying concentrations of aluminum and manganese impurities (0.01-0.04M) were grown on glass substrates at room temperature in a chemical bath containing Tin II chloride, sodium thiosuphate, sodium ethylene diaminetetra acetate EDTA, ammonia and sodium tri-citrate. The optoelectronic properties of all the films were analyzed using a spectrophotometer and four point probe. The results show generally low transmittance and reflectance with the highest increase of 3% in transmittance occurring for 0.01M of aluminum and 0.02M of manganese impurities. The reflectance increased to 9% for 0.04M of aluminum and 15% for 0.02M of manganese impurities while 0.01M of both impurities lowered the reflectance. The absorbance for all impurity concentrations converged from a high value of 1.0 in the UV region and decreased marginally to a minimum of 0.82 for 0.02 M of manganese impurity in the visible region. Absorption coefficients increased with impurity concentration for both impurities. Also, the direct energy band gap increased with impurity concentration from 1.50 eV for as grown thin film to (1.70-1.90 eV) for various concentrations of both impurities. Changes with impurity concentrations in the values of refractive index, optical conductivity and dielectric constant etc. are also reported here. Results of the four point probe revealed increase in electrical resistivity for both manganese and aluminum impurities, with a maximum at 0.03 molar