Thermal annealing effects on the optoelectronic characteristics of fully nanowire-based UV detector

We report on the fabrication of fully nanowires-based photodetectors whose active parts were made of GaN nanowire and the electrodes made of Ag nanowire networks that provide both transparency and flexibility. The comparative investigations of two types of photodetectors in one case GaN nanowires experienced thermal annealing and another did not are performed. Long Ag nanowires were successfully synthesized through microwave-assisted multistep growth and GaN nanowires were grown by chemical vapor deposition. Observing the morphology of GaN nanowires by SEM, the length of most nanowires can reach 10 mu m. Via the proper thermal annealing process, the rise and fall time of photo-response of the photodetector has considerable improvement both in air and vacuum. At the bias of 1 V, the dark current of the nanowire-annealed photodetector has reduce to 2.6 x 10(-7) a"<<, which only takes 41.3 % of the dark current of the device without nanowires annealing. The mechanism of the optical response process and the performance of the two devices in different test environment are explained.