Theoretical Study On Electrical Properties Of Two-Dimensional Graphene-Metal Contacts

When constructing a nanoelectronic device based on a two-dimensional Graphyne material,the two-dimensional semiconductor material needs to be in contact with the metal electrode to form a semiconductor-metal junction.The contact of the metal with the two-dimensional semiconductor material has a great influence on the functional realization and performance of the device.In this paper,the electrical contact behavior of two-dimensional Graphyne GD with metals Au,Al,Ti,Ag is simulated,and GD/Al(111),GD/Au(111),GD/Ti(0001),GD/Ag(111)are simulated.Energy band structure,density of states,differential charge density,Mulliken charge distribution in the interface,analysis of charge transfer,band stracture and contact resistance between graphyne and metal electrodes,and select Graphyne/metal contacts with ohmic contact.The structure reveals the intrinsic properties of two-dimensional Graphyne and metal contact from the perspective of electronic structure,and provides theoretical guidance for the experimental preparation of two-dimensional Graphyne-based nanoelectronic devices.The main contents and conclusions of the thesis are as follows:(1)We constructed and optimized the two-dimensional Graphyne(GD),Al(111),Au(111),Ti(0001)and Ag(111)surface models,caculated the electronic structure of GD was.The results show that the two-dimensional Graphyne is a direct band gap semiconductor,and its valence band top and conduction band bottom are located at the M point of the Brillouin zone.The 6atomic thickness layers can correctly describe Al(111)and Au.(111),Ti(0001),Ag(111)surface,vacuum layer thickness is 20?.(2)We constructed GD/Al(111),GD/Au(111),GD/Ti(0001),GD/Ag(111)interface models respectively,and simulated GD/Al(111),GD/Au(111),GD/Ti(0001),GD/Ag(111)interface contact area electronic structure,including band structure,state density,differential charge density,Mulliken charge distribution.The results show that GD is in physical contact with the surface of Al(111),Au(111)and Ag(111).The adsorption energy Eb is small and the adsorption distance dC-M is large.The surface of GD and Ti(0001)is chemical contact,and have a big adsorption energy E_b,a small adsorption distance dC-M,and have negative contact barrier,which is ohmic contact,and the contact resistance of GD/Ti(0001)is the smallest,which is suitable as Conductor wire to connecting Graphyne.