Comparative study of ZnTe thin films prepared using close space sublimation (CSS) and electron beam evaporation (EBE) thin film fabrication techniques for optoelectronic applications

Abstract

ZnTe thin films were deposited onto soda lime glass substrates by the close space sublimation (CSS) and electron beam evaporation (EBE) techniques under vacuum (as deposited, annealed at 300 °C and Ag doped for 10 min). Structural, morphological, optical and electrical properties of ZnTe films were studied before and after doping. The ZnTe thin films fabricated by EBE technique showed improvement in microstructure, morphology, crystalline orientation and physical parameters such as porosity and density as compared to CSS fabricated thin films. The highest density with very small porosity is observed in EBE fabricated films. The improvement in electrical parameters such as resistivity, mobility, sheet concentration, type of semiconductor (p or n type), bulk concentration and magnetoresistance were observed in EBE fabricated thin films. The highest decrease in electrical resistivity (8·34×102 Ω cm) was observed by incorporating Ag dopant via EBE technique. The main purpose of this was a comparative study between EBE and CSS techniques and an improvement in the electrical and optical properties such as electrical conductivity, mobility, sheet resistance/concentration and the band gap of the fabricated thin films. The doping of Ag was performed to observe their effects on morphology, structure, electrical and photovoltaic properties of the as deposited thin films. It was observed that electrical and optical properties of the fabricated films enhanced with dopant and annealing temperature.