Research On Two-dimensional Material Infrared Detector Based On Surface Plasmon Enhanced Nanostructure

Since the discovery of graphene,two-dimensional materials have attracted scientific attention due to their excellent optical and electrical properties,and have been used in the research of photoedetectors.However,the ultra-thin thickness of the two-dimensional material makes its weak light absorption,which limits the further improvement of its detection performance.Surface plasmon possess the properties of breaking through the optical diffraction limit and achieving nanometer focusing,which provides a new method for improving the performance of photodetector.In our present study,with utility of controlled growth and self-assembly method,the metal nanoparticles have been prepared and transfered to MoS₂ detector,which has improved the absorption of infrared light of the device,enhancing the responsivity and other performance parameters.The specific research work of this study is as follows:1.The detection performance and response mechanism of MoS₂ detector in infrared region was focused.Firstly,the MoS₂ detector was prepared and the performance parameters of the device were measured and calculated.Under the incident light of 808 nm,the responsivity of the MoS₂ photodetector was up to 1.55A/W,and the specific detectivity was up to 1.1×10¹⁰ Jones.Under the incident light of980 nm,the maximum responsivity is 0.53 A/W,and the maximum specific detectivity is 3.39×10⁹ Jones.According to the analysis of the experimental results,the MoS₂detector is mainly based on the photogating effect under 808 nm incident light and follows the positive response mechanism.Under 980 nm incident light,the MoS₂detector follows a negative response mechanism based on bolometer effect.In addition,the influence of MoS₂ thickness on the detection performance is studied.The results showed that the detector with larger thickness of MoS₂ has higher responsivity,but lower specific detectivity.2.The controlled preparation of the surface plasmon metal nanostructures was mainly discussed.By controlling the amount and proportion of the solution we used,the silver nanoplates with controllable morphology and size were prepared,and the surface plasmon resonance peak was controlled in the range of visible to near-infrared(480 nm-827 nm).Furthermore,the precise adjustment of the ratio of the solution was further studied,and the precise regulation of the surface plasmon absorption peak was completed,which provided a basis for the further enhancement of the detection performance at specific wavelength.3.The MoS₂ detector with surface plasmon structure is studied.Firstly,the silver nanoplates were transferred to the surface of MoS₂ detector by self-assemble process,so the surface plasmon nanostructure decorated MoS₂ detector was prepared.Then,the performance of the detectors before and after the introduction of silver nanoplates was tested and compared.Results showed that the silver nanostructure increases the light absorption of MoS₂,improved the performance of the detector obviously.The responsivity of the detector increases from 1.55 A/W to 4.59 A/W after assembling the silver nanoplate structure,which increases by 1.96 times.And the specific detectivity increases from 9.9×10⁹ Jones to 1.06×10¹⁰ Jones.In addition,we studied the effects of distribution density and different sizes of nanoplate on enhancing the performance of MoS₂ detector.Results showed that silver nanoplate with the greater distribution density has a more obvious performance improvement on MoS₂ detector,The silver nanoplate with resonance peak position closer to the incident light has more outstanding enhancement.