High-Performance InSe Photodetector Induced by Synergetic Surface Plasmon Resonance and Surface Engineering

Abstract

Indium selenide (InSe) has gained extensive research attention due to its unique structure and broad tunable optical response in the visible to near-infrared range. However, InSe has a low optical absorption rate due to its intrinsic indirect bandgap nature and is easily affected by ambient air and water vapor, thus limiting its photoelectric performance. In this work, we significantly enhanced the photoelectric performance of the InSe photodetector by taking advantage of the synergetic effect of both surface plasmon resonance (SPR) and surface engineering. The former is induced by an array of gold nanoparticles (Au NPs) placed under the InSe channel, while the latter is realized by a 20 nm In layer deposited on the InSe layer surface. The responsivity of such an In/InSe/Au NP-based photodetector reaches 15.2 A/W at 637 nm, 3 orders of magnitude higher than that of the In/InSe photodetector and 4 orders of magnitude higher than the original InSe photodetector. The response speed achieves 1.75 ms, representing a three-order-of-magnitude improvement over the original InSe photodetector. This enhancement can be attributed to the increased surface charge transfer and the localized SPR, which couples with the out-of-plane polarized InSe bandgap excitons, enhancing the light−matter interaction of InSe. Raman spectroscopy and photoluminescence (PL) spectroscopy analyses confirmed significant surface charge transfer at the In−InSe interface and enhanced PL due to the presence of Au NPs. Therefore, our work provides an effective pathway for improving the optical properties of InSe, taking an important step toward its practical application in optoelectronic devices.