Topological Bi2Se3/n-GaN Hybrid Structure for Enhanced and Self-Powered UV Photodetectors

Recent progress in topological insulating materials predicts a promising future for their applications in developing innovative quantum, electronic, and optoelectronic devices. The integration of topological insulators with technologically important semiconductors can open up different ways to build high-efficiency devices. Here, we have fabricated topological insulator Bi 2 Se 3 /GaN hybrid structure-based photodetectors (PDs) and studied their photoresponse characteristics in the ultraviolet (UV) region. Raman and high-resolution X-ray diffraction spectroscopy measurements revealed the formation of the c -axis-oriented rhombohedral crystal structure of the Bi 2 Se 3 film. X-ray photoelectron spectroscopy studies disclosed the formation of a stoichiometric Bi 2 Se 3 thin film on n-GaN. The Bi 2 Se 3 thin film with the magnetotransport property exhibits a metallic nature with an upturn in resistivity below 20 K which possesses a weak antilocalization effect under an applied magnetic field, confirming the topological insulating behavior. Further, we have fabricated metal–semiconductor–metal-type PD devices on the hybrid structure of Bi 2 Se 3 /n-GaN, Bi 2 Se 3 /n-GaN junction, and pristine n-GaN. The photoresponse measurements have been performed using a UV (355 nm) light source by varying the laser power (1–15 mW) and the external bias (0–5 V). The calculated value of photoresponsivity of the PD devices on the Bi 2 Se 3 /n-GaN hybrid structure is found to be seven-fold higher than that of pristine-GaN. Further, it is observed that devices consisting of a Bi 2 Se 3 film and GaN show self-powered UV PD characteristic nature. This study adds a significant step to enhance the performance of UV PDs based on large-area GaN templates by several folds with the help of topological Bi 2 Se 3 /GaN hybrid structures.