Opto-electrical characterisation of In-doped SnS thin films for photovoltaic applications

Abstract

Spray pyrolised SnS thin films doped with indium were studied using various optical and electrical techniques. Structural analysis shows that all films crystallize in orthorhombic structure with (111) as a preferential direction without secondary phases. Doping of SnS layers with indium results in better morphology with increased grain size. Absorption measurements indicate dominant direct transition with energy decreasing from around 1.7 eV to 1.5 eV with increased indium supply. Apart from direct transition, an indirect one, of energy of around 1.05 eV, independent on indium doping was identified. The photoluminescence study revealed two donors to acceptor transitions between two deep defect levels and one shallower with energy of around 90 meV. The observed transitions did not depend significantly on In concentration. The conductivity measurements reveal thermal activation of conductivity with energy decreasing from around 165 meV to 145 meV with increased In content.

Evaluation of SnS:Cu Thin Film Properties Obtained by USP Technique to Implement It as an Absorbent Layer in Solar Cells Using SCAPS

“…Consequently, the resistivity decreases as the doping percentage of the films increases. This behavior has been detected in other work [9] for the same doping agent Cu and other elements like In and Sb [5,39]. This reduction in resistivity could be attributed to the excess charge created by an increased Sn/S atomic percent ratio.…”