Optical and electrical characterization of ZnS:Sn thin films for solar cell application

Abstract

Tin Doped Zinc Sulphide (ZnS:Sn) thin films are a special kind of material that exhibit electrical conductivity and at the same time, high transmittance in visible region making it suitable for Solar Cell applications. To study the effect of Sn doping on optical and electrical properties of ZnS thin films, a series of investigations were made. Thin films were deposited on glass substrate from ZnCl 2 , and SC (NH 2 ) 2 , in ammonium solution with different low tin concentration, utilizing a chemical bath deposition technique. Optical and electrical characterization of the films with different amounts of dopant was carried out using UV-VIS-NIR spectrophotometer Solid State 3700 DUV and Four Point-Probes. All films demonstrated transmittance above 70% for wavelength above 540nm. On average reflectance was below 25% for the same wavelength. Electrical resistivity increased with increase in Sn ion concentration and it ranged between, 9.62 × 10 1 Ω-cm to 1.19 × 10 2 Ω-cm. A comparison of the obtained results revealed that low concentration of Sn doping improves transmittance of ZnS films and makes them suitable for application as window layer of ZnS:Sn/CuO solar cell.

Keywords Chemical Bath Deposition, Transmittance, Reflectance, Sn doped ZnS, Electrical Properties