Electronic And Optoelectronic Properties Of Two Dimensional MoSe₂

Studies on graphene have aroused people’s interests on other two dimensional（2D）materials,especially the transition metal dichalcogenides（TMDs）.Unlike their bulk counterparts,2D TMDs have been discovered to hold many extraordinary properties.As a new 2D TMD,MoSe₂ is promising in electronics and optoelectronics because of its unique energy band structure.Currently,studies related to 2D MoSe₂ mainly concentrate in the catalysis field,and usually the MoSe₂ is in powder form or is polycrystalline and doped.Researches on 2D monocrystalline MoSe₂ can bring more possibilities to application in electronics and optoelectronics.Meanwhile,it is a foundation for studies of heterostructures and other aspects based on 2D MoSe₂.As for scientific significance,this is beneficial for exploration of the relationship between structure and properties.It may also enable us to tune the electrical and optical properties of 2D monocrystalline MoSe₂.Starting from the production of 2D monocrystalline MoSe₂,we develop the following works with many fabrication and measurement equipments:1.By exposing 2D MoSe₂ to certain dose of 10keV electron beam under high vaccum(about 10^-5mbar),we study the influence of electron radiation on 2D MoSe₂’s optical spectrum characteristics.We find that electron radiation changes Raman and Photoluminescence spectrum of monolayer and bilayer MoSe₂,but makes no difference to multi-layer MoSe₂;2.By fabricating heterostructure of MoSe₂ and graphene,we study effects of graphene’s coupling on 2D MoSe₂’s optical spectrum characteristics.Results show that there may exists charge transfer between MoSe₂ and grapheme,which depresses the Photoluminescence intensity of MoSe₂;3.We compare the output characteristics and transfer characteristics of field effect transistors based on different layer 2D MoSe₂.Also,we explore the temperature’s influence on performance of MoSe₂ transistors.The lowest experimental temperature approaches 0.3K;4.Employing laser of several wavelength to test optoelectronic properties of MoSe₂ transistors,we discover that few-layer MoSe₂ transistors possess higher photoresponsivity of red light than that of blue light.