Universal Strategy Integrating Strain and Interface Engineering to Drive High‐Performance 2D Material Photodetectors

Abstract 2D indium chalcogenides including α‐In₂Se₃ and InSe are promising candidates for next‐generation optoelectronic devices. However, the performance of traditional SiO₂‐supported devices is limited because of the detrimental effect of the substrate, which greatly restricts charge transportation. Although the induction of an internal (built‐in) electric field can alleviate this situation, the application of conventional stacking technology required in this case inevitably introduces interface defects. Against this backdrop, in this study, a simple and universal structure for the fabrication of highly sensitive photodetectors is designed and engineered. A SiO₂ window to afford a “suspended” α‐In₂Se₃ channel, effectively eliminating the detrimental effects of the substrate, is etched. In addition, the approach induces local strain in the suspended α‐In₂Se₃, which regulates the band structure and introduces intramolecular type‐II alignment. Thus, the interfacial charge transfer is optimized, and the photodetection performance is enhanced. The resulting device exhibits excellent photosensitivity (responsivity of 1672 A W⁻¹, on/off ratio of 263, and detectivity of 7.5 × 10¹³ Jones), and a relatively fast response rate (12 ms for both rise and decay). This structure can also be extended to InSe devices to comprehensively enhance their photodetection performance, thereby demonstrating the broad applicability of the proposed method.