The fabrication and UV photosensitive characteristics of Al/ZnO/Ag Schottky barrier diode

In this paper, n-type ZnO thin film was grown on single crystal Si ( 111 ) substrates by RF magnetron sputtering and high temperature annealing in vacuum. X-ray diffraction(XRD) and scanning electron microscope(SEM) were used to investigate film qulity and the structural performance. The results show that ZnO thin film is well c-axis oriented and the surface of ZnO is very clean and smooth. In the same conditions of depositing ZnO thin film, a vertical structure of Al/ZnO/Ag Schottky barrier diode detctor was designed and fabricated on the quartz glass substrate. The characteristics of dark-and photo-current of the Schottky UV photodetector was investigated. The results of testing at room temperature indicate that there is a good Schottky behavior between Ag and ZnO, the effective barrier height was determined to be 0.60 and 0.53eV by current-voltage and capacitance-voltage measurements respectively. The ideality factor was found to be 12.6, theoretical calculation of the space charge density was 3.1×10¹⁶ cm^-3. At a bias of 3V, dark current was 24.19mA without illumination. Under illumination using monochromatic light with a wavelength of 365 nm, photogenerated current arrived at 3.28mA, at a bias of 3V, suggest that Al/ZnO/Ag UV photodetector has a significantly light response characteristics.