Quasi-Symmetric Wheatstone Bridge Zinc Oxide Nanorod UV Detectors

Zinc oxide (ZnO) nanorod-based ultraviolet (UV) detectors have high responsivity at room temperature due to carrier generation assisted by the depletion region formed by oxygen adsorbed on the surface of nanorods. As such, the amount of oxygen adsorbed on the ZnO nanorod surface and the number of electron-hole pairs that reaches the depletion region on the surface can change the response of the detector. In this paper, the transient responses of metal-semiconductor-metal ZnO nanorod-based UV detectors based on a quasi-symmetric Wheatstone bridge configuration were investigated. Responsivity, defined as the ratio of the Wheatstone bridge detector output current to the total power of the UV light incident on the active area of the detector, as high as 54 A/W was obtained in some of these UV detectors at 30 °C. It was found that the responsivity and the temperature effects on the UV response of the Wheatstone bridge ZnO nanorod UV detectors can be tailored by the difference in the diameters and lengths of the rods grown in the two quadrants.