Band offset engineering and interface carrier transport optimization in GeO2/ β -Ga2O3 heterostructures for high-performance self-powered solar-blind photodetectors

Ultra-wide bandgap semiconductor GeO2/β-Ga2O3 heterostructures are attracting growing attention as potential candidates for achieving solar-blind ultraviolet detection applications. However, the unfavorable conduction and valence band barriers at the heterostructure interface severely hinder the development of high-performance GeO2/β-Ga2O3 heterojunction self-powered solar-blind photodetectors (SP-SBPDs) due to the unimpeded transport of thermally activated electrons and the accumulation phenomenon of holes. Here, a GeO2/β-Ga2O3 heterostructure with a SiO2 insertion layer has been designed to fabricate 213 nm SP-SBPDs, in which the inserted SiO2 layer effectively suppresses thermal carrier transfer in the dark and regulates photogenerated carrier transport through the introduced band offsets. Compared with the GeO2/β-Ga2O3 SP-SBPD, the GeO2/SiO2/β-Ga2O3 SP-SBPD achieves a 129-fold reduction in the dark current and a 3.3-fold enhancement in photon-to-dark-current ratio without applied bias. Moreover, the GeO2/SiO2/β-Ga2O3 device also exhibits a larger detectivity of 3.11 × 1012 Jones and faster rise/fall times of 109/75 ms, which enables self-powered solar-blind UV imaging with a quality factor of 9.8 and a bit error rate of 2.81 × 10−2. Our experimental results demonstrate the potential of the GeO2/SiO2/β-Ga2O3 SP-SBPDs for solar-blind UV imaging, optical communication, and information encryption applications.