On the Responsivity of UV Detectors Based on Selectively Grown ZnO Nanorods

Recent studies have shown that zinc oxide (ZnO)-based ultraviolet (UV) photodetectors have better sensitivity and can be fabricated cheaply and compactly. To know whether the responsivity of these types of UV photodetectors can be improved by manipulating the dimension of the electrodes and length of the nanorods, we investigated the dependence of dark current and responsivity of the metal-semiconductor-metal (MSM)-type ZnO detector on those factors. The MSM ZnO nanorods based detector was designed compactly by arranging the interdigitated electrodes in a square form resembling a Wheatstone bridge where ZnO nanorods with diameters ranging from 20 to 70 nm were prepared by hydrolysis method. The crystallinity and surface morphology of the rods determined using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively, are also discussed here. We observed that the responsivity of the detector measured for a UV wavelength of 365 nm depends on the spacing between electrodes, width of the electrode, and length of the nanorod.