Topological Bi<sub>2</sub>Se<sub>3</sub>/n-GaN Hybrid Structure for Enhanced and Self-Powered UV Photodetectors
Rahul Kumar, Vishnu Aggarwal, Aditya Yadav, Sudhanshu Gautam, Sandeep Singh, Ramakrishnan Ganesan, V. P. S. Awana, Govind Gupta, M. Senthil Kumar, Sunil Singh Kushvaha
Abstract
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.