Ultrahigh responsivity solar-blind high electron mobility photodetector utilizing a β-Ga2O3/GaN heterojunction

Abstract

β gallium oxide (β-Ga₂O₃) is considered as a primary choice for solar-blind ultraviolet (SBUV) detection because of its advantages such as intrinsic solar-blindness and robust stability. Nevertheless, the inherent low electron mobility of β-Ga₂O₃ poses a significant challenge to its application. Here, β-Ga₂O₃ films were integrated with gallium nitride (GaN) substrates through metal-organic chemical vapor deposition (MOCVD). Based on the obtained heterojunctions, a solar-blind high electron mobility photodetector (HEMPD) was developed. With the help of the minimal conduction band offset (0.12 eV), the photo-generated carriers are able to almost unhindered move between β-Ga₂O₃ and GaN, and drift in GaN under an external field. Leveraging the high electron mobility advantage of GaN, the HEMPD achieves a responsivity (R) of 2.96 × 10⁴ A/W and an external quantum efficiency (EQE) of 1.44 × 10⁷ %, even surpassing some β-Ga₂O₃-based avalanche photodetectors (APDs). Furthermore, the indirect contact between GaN and electrodes significantly improves the SBUV/UV-A rejection ratio of our HEMPD compared to other vertical PDs based on β-Ga₂O₃/GaN heterojunctions. This study provides crucial insights for overcoming the low electron mobility limit of β-Ga₂O₃-based PDs.