This study investigates the effect of interfacial electric field redistribution caused by interfacial metal phase transition on the performance of Te-Se alloy-based shortwave infrared photodiode under high interfacial stress conditions. Microscopic analysis of the Te_0.6Se_0.4/ZnO interface reveals that stress at the boundary induces the diffusion of Se atoms into the ZnO region, leading to the formation of a new Te-rich metallic phase of Te_0.75Se_0.25. This metallic phase would significantly impede carrier migration and negatively impact the photoelectric performance of the device. The incorporation of a TeO₂ modified layer would reduce interface stress, and avoid the formation of the metallic phase, which notably reduces dark current and enhances quantum efficiency. This study explores how interfacial stress influences the structure–property relationship of TeSe/ZnO heterojunctions, offering a novel approach to optimizing interface engineering for Te-based infrared detectors.