Optical Resonance Coupled with Electronic Structure Engineering toward High‐Sensitivity Photodetectors.

Ultrasensitive photodetectors with high responsivity, detectivity, and fast response rate have triggered urgent demand in extensive applications. In recent years, 2D indium chalcogenides have emerged as appealing photoactive materials due to their excellent electrical and optoelectronic properties. However, suffering from the weak optical absorption induced by atomically thin thickness as well as the short lifetime of photogenerated carriers, conventional 2D indium chalcogenides photodetectors commonly exhibit limited photodetection performance. Herein, a universal strategy integrating 2D indium chalcogenides and Si nanostripe array is demonstrated. The Si nanostripes afford Mie‐type resonance, which facilitates light absorption. In addition, the introduction of photoconductive gain and strain engineering prolongs photogenerated carriers' lifetime and accelerates their transport. The coupling effect of these three mechanisms enables the device to exhibit high photodetection performance. The constructed α‐In2Se3 device manifests a high responsivity of 9.4 × 103 A W−1, detectivity of 5.5 × 1013 Jones while maintaining fast rise/decay time of 2.7/3.8 ms. In addition, this proposed strategy can also be employed to construct InSe device with comprehensively enhanced photodetection performance, which presents universality and wide applicability. These results demonstrate that advanced device design is an effective avenue to achieve future multifunctional optoelectronic devices with high sensitivity. [ABSTRACT FROM AUTHOR]