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Monolayer MoS2 Photoluminescence Enhanced Device And Field Effect Tube Device Based On Localized Surface Plasmons Effect

Posted on:2021-06-01Degree:MasterType:Thesis
Country:ChinaCandidate:J Y KangFull Text:PDF
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Optical devices and optoelectronic devices based on two-dimensional materials have the advantages of small size,high sensitivity,and can be made into flexible devices,wherefor they are considered to be the future development direction of such devices.Monolayer MoS2 is a typical two-dimensional material,which consists of two layers of S atoms and one layer of Mo atoms,and the thickness is about 0.65 nm.It is a direct band gap semiconductor with a band gap width of 1.8 e V.This gives a monolayer MoS2 strong photoluminescence(PL)properties,also provides a possibility for the application of monolayer MoS2 in field-effect transistor(FET)devices.However,monolayer MoS2 can only absorb up to 10%of incident light in the visible light band,which results in its PL intensity and photoelectric response often failing to meet the requirements of practical applications.Using metal nanoparticles to generate localized surface plasmon(LSP)effects is an effective way to solve this problem.But the traditional methods for preparing metal nanoparticles on two-dimensional materials generally have the disadvantages of low particle density,large gap width and complicated preparation methods.Therefore,it is particularly important to propose new methods for preparing metal nanoparticles.In this context,we propose a method for preparing the Ag nanoparticle based on Electron Beam Evaporation(EBE)system.Based on this method,a monolayer MoS2 PL enhancement device and a FET device are designed and manufactured,which enhanced the monolayer MoS2PL properties and FET performance respectively.The corresponding enhancement mechanism is studied.The main contents of this dissertation are shown as follows:(1)A monolayer MoS2 photoluminescence enhanced device based on silver nanoparticles was designed and manufactured.The structure of this device is a sandwich-like structure.The upper and lower layers of silver nanoparticles are separated by a thin Al2O3 dielectric layer and a single layer of MoS2 by wet transfer method.The core is a stacked structure of double-layered silver particles that generates a dense LSP effect hot spot,which greatly enhances the interaction between light and matter.This monolayer MoS2 photoluminescence enhanced device achieved203 times enhancement of photoluminescence.Characterized and analyzed the micro-morphology of this device and its derivative control device,tested the PL spectrum of the prepared devices,and selected different PL spectrum control groups for analysis the role of each part of the device;Finite difference time domain method(FDTD)was used to simulate the structure,revealing the reason why the double-layer silver particles have super strong PL enhancement;The Raman spectrum of MoS2 in the device is analyzed,and it is proved that the morphology of the upper silver particles in the sandwich structure is directly related to the surface state of MoS2 after transfer.(2)A monolayer MoS2 FET device modified with silver nanoparticles was designed and manufactured.Compared with ordinary monolayer MoS2 FET devices,the modified device has parameters such as switching ratio and saturation current in the presence or absence of light were improved,especially in laser irradiation.The mechanism of this enhancement effect can be attributed to the fact that the surface plasmon effect produced by the silver nanoparticles makes the carriers in monolayer MoS2 more excited under laser irradiation.Besides,this dissertation also introduces the basic theory,research background and research progress of LSP,MoS2 photoluminescence,FET devices and other fields,as well as the instruments and principles used in the experimental process.These works are of great significance to the theoretical research of two-dimensional materials and device manufacturing in practical production.
Keywords/Search Tags:Monolayer MoS2, Localized surface plasmon, PL enhancement, FET
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