Optimized 2D Bi2Se3 thickness for broadband, high-performance, self-powered 2D/3D heterojunction photodetectors with multispectral imaging capability

The hybrid 2D/3D heterostructure, which synergistically combine the high surface area and superior surface properties of 2D materials with the volumetric advantages and mechanical stability of 3D materials, offer an efficient and unique platform for electronic, optoelectronic, and energy conversion applications. Although this structure offers numerous advantages, optimizing the performance of 2D/3D heterojunction devices still faces challenges such as interface control difficulty, doping uniformity, and scalability for mass production. To simplify and effectively optimize the performance of 2D/3D heterojunction devices, this study delves into the impact of the thickness of 2D Bi2Se3 films on the performance of Bi2Se3/GaN heterojunction photodetectors. In thinner Bi2Se3 films, a higher surface defect density increases carrier recombination efficiency, while in thicker films, an increase in internal defects impedes carrier transport. Our findings reveal an optimal film thickness that balances surface and internal defects, enhancing carrier dynamics and device performance. Remarkably, the Bi2Se3 (14.8 nm)/GaN heterojunction detector exhibits superior broadband response from ultraviolet to near-infrared, with a maximum responsivity of 0.07 A/W, a detectivity of 1.79 × 1012 Jones, and an on/off ratio of 1.02 × 104. Additionally, the device demonstrates prolonged stability in response and multispectral imaging capability. This research not only underscores the critical role of film thickness in modulating device performance but also provides novel theoretical and practical guidance for designing high-performance, self-powered, broadband heterojunction photodetectors, offering significant implications for scientific research and practical applications.