Advancements in Ga2O3-based heterojunction ultraviolet photodetectors: Types, fabrication techniques, and integrated materials for enhancing photoelectric conversion efficiency

Ga2O3-based heterojunction photodetectors integrate Ga2O3 with partner semiconductors via deposition techniques to obtain a high-quality interface, resulting in minimizing recombination losses and maximizing the external quantum efficiency of the device. Ga2O3-based heterojunction photodetectors enhance photoelectric conversion efficiency through the formed built-in electric field. Furthermore, the heterojunction photodetectors could operate in a self-powered mode, detecting light signals without external power sources. This review provides a comprehensive summary of the heterojunction types in Ga2O3-based photodetectors, covering both non self-powered (MSM) and self-powered (n-n, p-n, and p-i-n) configurations. It also details the geometric configurations, including planar, quasi-vertical, and vertical types. In addition, the review also provides an overview of various fabrication techniques employed for these photodetectors, including chemical vapour deposition, magnetron sputtering, mechanical exfoliation, and molecular beam epitaxy. The materials utilized in fabricating Ga2O3-based heterojunctions photodetector are also discussed, encompassing doped Ga2O3, nitride, graphene, MXenes, oxides, chalcogenides, organic materials, and perovskites. The review further addresses the challenges and future directions for Ga2O3-based heterojunctions. Future research is anticipated to focus on enhancing the quality of Ga2O3 crystals, exploring new materials for heterojunction construction, increasing lattice matching, and developing ultrathin devices. The key priority is to propose an enhanced strategy to address the challenges encountered by Ga2O3-based heterojunction photodetectors in practical applications (environmental monitoring, space exploration, industrial process monitoring, biomedical imaging, defense and security). In conclusion, creating heterojunctions is an effective approach to significantly enhance the photoelectric conversion efficiency of UV photodetectors.