Preparation and Characterization of p-Ag2O/n-Si Heterojunction Devices Produced by Rapid Thermal Oxidation

The thermal evaporation system type (Edwards) has been used to evaporate high purity (99.9%) silver on quartz and (n-type) silicon substrates at room temperature under low pressure (about10-6torr) for different thickness (50, 100, and 150) nm. Using a rapid thermal oxidation (RTO) of Ag film at oxidation temperature 250 oC and oxidation times 60 sec, Ag2O thin film was prepared. The structural, optical and electrical properties of Ag2O film were investigated and compared with other published results. The structural investigation showed that the films formed at thickness 150 nm showed (111) strong reflection along with weak reflections of (200) and (103) correspond to the growth of single phase Ag2O with cubic structure. Optical properties revealed that these films having direct optical band gap of (2.4, 2.3, 2.1) eV at different film thickness with high transparency in visible and NIR regions. Dark and illuminated I-V, CV, and spectral responsivity of p-Ag2O/n-Si heterojunction were investigated and discussed. Ohmic contacts were fabricated by evaporating 99.999 purity aluminum and gold wires for back contact and front contact respectively. Ag2O thin film was also prepared on n-type indium tin oxide (ITO) thin films to investigate the I-V characteristic of p-Ag2O/n-ITO junction.