ZnO-based interdigitated MSM and MISIM ultraviolet photodetectors

The paper reports the fabrication and characterization of ZnO-based interdigitated metal–semiconductor–metal (MSM) and metal–insulator–semiconductor–insulator–metal (MISIM) ultraviolet photodetectors. The ZnO thin film was grown on a p-type Si ⟨1 0 0⟩ substrate by the sol–gel technique. With applied voltage in the range from −3 to 3 V we estimated the contrast ratio, responsivity, detectivity and quantum efficiency of the photodetectors for an incident optical power of 0.1 mW at 365 nm ultraviolet wavelength. The I–V characteristics were studied and the parameters such as ideality factor, leakage current and barrier height were extracted from the measured data. For Au/Cr/SiO2/ZnO/SiO2/Al (MISIM) structure the product (mχ) of the tunnelling effective electron mass (m) and the mean tunnelling barrier height (χ) was also extracted.