Influence of substrate temperature on the SnS absorber thin films and SnS/CdS heterostructure prepared through aerosol assisted nebulizer spray pyrolysis

In this study, we explored the consequence of temperature on the SnS films prepared from aerosol assisted spray pyrolysis method on glass substrate. All the deposited films were analyzed using x-ray diffraction, Fourier transforms Raman spectroscopy, scanning electron and atomic force microscopy, computer controlled UV-vis spectrophotometry and photoluminescence spectrofluorometry. Hall Effect measurement was done to divulge the electrical properties of the film. Structural parameters such as crystallite size, micro strain, dislocation density and lattice structure were estimated using XRD analysis. There was a notable enhancement in morphology and surface roughness of the films and they were found to vary with respect to the substrate temperatures. When the substrate temperature was augmented from 300 to 350 °C, the energy gap showed a decrement from 1.7 eV to 1.56 eV. The lowest value of resistivity ∼2.1 ×10¹ Ω cm and a higher carrier concentration ∼4.09 ×10¹⁷ /cm³ were observed from 350 °C for the prepared SnS thin films along with p-type conductivity. The same method was employed to prepare CdS films with an observed transmittance of 70% and an optical band gap of 2.75 eV. Heterostructure comprising of p-SnS/n-CdS, fabricated using the grown films were also studied for their photovoltaic properties. The open circuit voltage (V _oc) got incremented from as low as 0.07 to 0.175 V and short circuit current (I _sc) from 0.65 to 3.45 μA when substrate temperature is increased from 300 °C to 350 °C.