FABRICATION AND CHARACTERIZATION OF GROUP II-VI SEMICONDUCTOR THIN FILMS

Abstract

ZnTe thin films were fabricated using Close Space Sublimation (CSS) technique. ZnTe films (as deposited, annealed and doped) were fabricated under vacuum on transparent glass slides. Structural, morphological, optical and electrical properties of ZnTe films were studied before and after annealing. The structure and morphology of the films were studied by XRD, SEM and the composition of the films was analyzed by EDX. Electrical characterization was done by the Hall Effect Measurement System. By this apparatus resistivity, mobility, sheet concentration, type of semiconductor (p or n type), bulk concentration and magneto-resistance were measured. Optical characterization was carried out by UV-Spectrophotometer. For all the fabricated films the various optical parameters e.g. thickness, transmission and band gap were calculated. The main purpose of this research was to improve the electrical properties and optical properties e.g. electrical conductivity, mobility, sheet resistance/concentration, band gap etc. of the fabricated thin films through CSS. The doping of various elements such as Ag and Cu was performed to observe their effects on morphology, structure, electrical and photovoltaic properties of the parent material due to their specific nature (n or p type) and as a function of various evaporation times of the doping elements. The evaporation of Ag and Cu was performed for different times under same annealing temperature and vacuum conditions. It was observed that electrical and optical properties of the fabricated films enhanced with dopant type and annealing temperature.