Detached Vertical (Al,Ga)N Nanowires to Realize the Flexible Ultraviolet Photodetector with High Ultraviolet/Visible Reject Ratio and Detectivity

Abstract

Flexible ultraviolet (UV) photodetectors (PDs) can meet the growing demands and wide applications of next‐generation portable and lightweight optoelectronic devices. Herein, a flexible UV PD based on (Al,Ga)N nanowires (NWs) is proposed and successfully fabricated by numerical and experimental approaches, which have high UV/visible reject ratio (1.5 × 104) and detectivity (8 × 1010 Jones). To accelerate the carrier transport and enhance the response, the top–down–top current pathway is demonstrated by introducing interdigitated electrodes and graphene. The UV/visible reject ratio of the flexible PD can be enhanced over 40 times by removing epitaxial silicon substrate to eliminate the corresponding visible response, leading to an excellent detection selectivity. By numerical simulations, the electric field intensities of the NWs are comparative in the unbending and bending states. After −120° bending, the PD performance remains quite stable. Under different bending states, the maximum variation of different response time can be kept within 0.15 s. According to the experimental data, the barrier height is essentially unchanged under different bending states, which should be a key factor contributing to the outstanding stability of the PD.