Optical and electrical properties of N-doped ZnO heterojunction photodiode

ZnO photodiodes consisting of high quality N-doped ZnO nanowires grown on n-GaN layer covered c-plane sapphire wafers were reported in this paper. The Au catalyzed ZnO nanowires were grown by chemical vapor deposition with excellent wurtzite structure. The I-V characteristics of the photodiodes show a rectifying diode behavior. Moreover, the pure ZnO/n-GaN sample was compared and analyzed to verify the p-type conductivity of heterojunction devices. We confirmed that such p-ZnO/n-GaN heterojunction devices exhibit distinct light emission when the electrode is applied with forward bias voltage. The lasing behavior of the p-n junction showed a threshold of 406 mW/cm2 by using optical pumping. The realization of p-type ZnO nanowire arrays with durable and controlled transport properties is important for the fabrication of nanoscale electronic and optoelectronic devices.