Surface-Oxidized Heterojunction In 2 O 3 /InN Core–Shell Nanorods on V-Grooved Si(111) for Enhanced Self-Powered Near-Infrared Photodetection

Self-powered (SP) III-nitride semiconductor-based near-infrared (NIR) photodetectors (PD) are essential components in applications such as night vision, optical communication, and biomedical sensing. However, the III-nitride-based PD achieving high sensitivity with low power consumption remains a challenge due to intrinsic material constraints and leakage current issues. In this work, we present an SP NIR PD based on In 2 O 3 /InN core–shell nanorods grown on V-grooved Si substrates. By integrating surface engineering at the heterointerface with optimized substrate geometry, the device achieves enhanced photoresponse and significant suppression of dark current. The built-in potential at the In 2 O 3 /InN interface effectively blocks thermally activated carriers, resulting in the lowest dark current of 1.4 × 10 –11 A and a magnificent light-to-dark current ratio exceeding ∼10 7 . Meanwhile, the V-grooved Si substrate improves light absorption through geometric confinement, while the core–shell architecture promotes efficient charge separation. Under 940 nm illumination and zero bias, the device exhibits a responsivity of 2.03 A/W, a detectivity of 7.30 × 10 13 Jones, and an external quantum efficiency of 2.68%. These results highlight the synergistic effects of surface passivation, heterostructure design, and substrate geometry in advancing next-generation SP NIR PD.