The light detection performance of ZnO-based Schottky-type photodetector as a function of changing solution molarity

Abstract

Wide band gap metal oxides can increase the detection band and performance of photodetectors. Among them, zinc oxide (ZnO) is a multi-functional oxide metal with various applications in various areas, that is, gas sensors, electronics, and optoelectronics. In this study, we employed ZnO metal oxide layers, which were synthesized by hydrothermal method, as interfacial layers for Schottky-type silicon-based photodetectors between Au metal and p-Si with 46 and 56 mM ZnO solution molarities to fabricate Au/ZnO/p-Si heterostructures. Synthesized ZnO morphology and crystallinity were tested by scanning electron microscopy and x-ray diffraction techniques. The Au/ZnO/p-Si heterostructures were investigated for photodetector applications by current-voltage (I-V) analysis in various light densities ranging from dark to 150 mW/cm2, and different wavelengths for the same light irradiance power. I-V characteristics under dark and light situations were used to extract diode characteristics and light detection parameters. The impedance analysis technique was also employed to demonstrate the capacitance behavior for the Au/ZnO/p-Si heterostructures. The obtained Au/ZnO/p-Si heterostructures confirms that trap levels are important to obtain high-performance photodetectors.