Self-powered broadband photodetector based on Bi2Se3/GaN pn mixed-dimensional heterojunction with boosted responsivity

Self-powered broadband photodetectors (SPBDs) have received considerable attention because of their significance in optoelectronic applications. However, limited by problems inherent to the material, such as high dislocation density, complex heteroepitaxy processing of bulk materials, and the small photoabsorption cross section in atomically thin layers of two-dimensional materials, SPBD photodetectors with both a wide detection range and attractive response characteristics are difficult to fabricate. To address this difficulty, herein the synthesis of n-Bi2Se3/p-GaN mixed-dimensional heterojunctions by the transfer method and their assembly into SPBD photodetectors are described. This photodetector offers both a wide spectral response range (ultraviolet to mid-infrared) and excellent response characteristics. The high responsivity (24554 A/W, 3V), remarkable Ion/Ioff (223.8), and rapid rise and decay times (τr = 0.063 s and τd = 0.043 s) benefit from both the built-in electric field of the pn junction and the fast electron transport on the surface of topological insulator Bi2Se3. The results of this research should facilitate the use of this emerging material for the design and fabrication of high-performance SPBD photodetectors.