MXene/AlGaN van der Waals heterojunction self-powered photodetectors for deep ultraviolet communication

Self-powered deep ultraviolet (DUV) photodetectors (PDs) have attracted considerable attention in environmental, industrial, and military fields because of their power-independent and environmentally sensitive photodetection. However, DUV PDs based on traditional thin film structures are limited by the low intrinsic mobility of aluminum-gallium nitride (AlGaN) and the large barrier width of the heterogeneous structure, which makes it difficult to achieve efficient spontaneous separation, resulting in lower responsiveness and a slow response speed. Herein, a 2D/3D DUV PD based on the MXene, niobium carbide (Nb2CTx)/AlGaN van der Waals heterojunctions (vdWHs) has been proposed. The as-prepared DUV PDs revealed self-powered properties with a high responsivity of 101.85 mA W-1, as well as a fast response (rise/decay time of 21/22 ms) under 254 nm DUV illumination, thanks to the excellent electrical conductivity and tunable work function of the MXene. It also showed a large linear dynamic range of 70 dB under -2 V bias because of the strong DUV absorption of MXene/AlGaN vdWH, and the enhanced carrier mobility under high illumination density. This study presents an easy processing route to fabricate high-performance self-powered DUV PDs based on MXene/AlGaN vdWHs for DUV communication.