The Study Of Optical And Photodetecting Properties Of Two-dimensional Molybdenum Ditelluride

As a new two-dimensional material,MoTe₂?Molybdenum Ditelluride?has attracted widely attention owing to its unique structure and excellent performance.MoTe₂ also exhibits a great potential in photodetecting applications due to its adjustable bandgap and good optical absorbability from visible to infrared region.In this paper,the optical and photodetecting properties of MoTe₂ prepared by the mechanical stripping method are mainly studied.The transition from semiconductor phase?2H?to semi-metal phase?1T'?of MoTe₂ is realized by laser irradiation.Heterostructures of Graphene and MoTe₂?Graphene/MoTe2?are fabricated by dry transfer to study the photodetecting properties.This dissertation contains four chapters and the contents are outlined as following.In chapter one,we first briefly reviewed the properties of two-dimensional MoTe₂material.Then,the basic principles,current status and trends of two-dimensional material photodetectors are also generally introduced.In chapter two,the contrast,Raman spectrum and photoluminescence spectrum of different layers of MoTe₂ are studied.The contrast of R channel of MoTe₂ increases linearly from 1 to 3 layers.Besides,the Raman spectra of different layers of MoTe₂ and photoluminescence spectra of different temperatures are generally studied.Also,the phase transition from 2H to 1T'of MoTe₂ is realized by laser irradiation.In chapter three,photodetectors based on multilayer MoTe₂ are fabricated via electron-beam lithography process.The photoresponses of the device with different laser power,bias,gate voltage and wavelength are measured.The photoresponsivity of our device is higher enough as⁵ A/W in visible range.The detectivity is calculated to be 1.5×10⁹ cm Hz^1/2W^-1 and the detection region is extended to 1.5?m.Heterostructures of Graphene/MoTe₂are fabricated via dry transfer method and the charge transfer of the heterostructures and its influence on optoelectronic properties are studied.In chapter four,we conclude the main results of this paper as well as prospect some future research work.