Si/SiO2/Ag optical sensor

Self-powered photo-detectors are of considerable interest in the internet of things and other domestic and industrial areas. Metal-semiconductor Schottky junctions have been widely applied as simple photo-detector, but high state density at the interface due to the interface imperfections and dangling bonds diminish the performance of these photodetectors. The solution of this problem is attempted by introducing a thin film insulator oxide layer between the metal and silicon which is usually the utilized semiconductor. Quality and thickness of this layer is the essential design and fabrication parameter. Silicon dioxide, thermally grown on silicon wafers and chips, is the most widely utilized insulator in silicon-technology. Here, we report using different thermal oxidation conditions for growing oxides of different thickness for the determination of the effect of oxide layer in the light detection sensitivity of Ag/n-type silicon/Al structure. Current-voltage characteristics, open-circuit voltage, and short circuit current are measured for different structures. The optimum oxidation condition is established to be 4 h at 900°C in humid conditions. The open circuit device generates 110 mV when illuminated with white light at ~0.5 mW/mm2 intensity.