The Optical And Electronic Properties Of Two-dimensional PtSe₂ Material And Its Heterostructure

Two British physicists successfully preparted Graphene from graphite,and obtained the Nobel Prize in physics,sparking a worldwide research boom.The novel mechanical and electrical properties of graphene make it have a wide range of applications potential.However,the properties of graphene zero band gap semimetals have limited its application potential.Therefore,researchers began to explore other two-dimensional materials as an alternative to graphene.In recent years,Graphene-like materials?such as,phosphene,arsenene?,layered transition metal dichalcogenides?such as,MoS2?,and h-BN have been successfully applied in photodetectors and field effect transistors?FET?,and they exhibit excellent photoelectric characteristics.Because single materials is difficult to meet the needs of the device,researches begin to build new two-dimensional materals,van der Waals heterostructures through stacking different materials,which not only overcome the disadvantages of single materials,but also improve the optoelectronic properties.The van der Waals heterostructures was synthesized experimentally by mechanical transfer or Chemical Vapor Deposition?CVD?.In this paper,we study the mechanical,electrical and optical properties of monolayer PtX₂?X=S,Se,Te?,as well as the electronic properties of PtSe₂/Graphene,PtSe₂/BN and PtSe₂/BN/Graphene heteromulityer.In addition,considering the stress and electric field are usually used in practical applications to control the properties of materials,we discusse the electronic properties of these materials under external electric field and strain in this paper.The main conclusions are as follows:Firstly,due to the same atomic configuration and spatial symmetry,monolayer PtS₂,PtSe₂ and PtTe₂ show similar shave similar mechanical,electrical,optical and other properties.The in-plane stiffness degrades gradually with increasing atomic number of chalcogenide atoms.The strain causes the optical absorption edge of monolayers PtS₂,PtSe₂,and PtTe₂ to red shift,that is,to towards lower energy.In addition,the monolayers of PtS2,PtSe2 and PtTe₂ achieves adjustable bandgaps within suitable biaxial strain range.Under tensile biaxial strain,monolayer PtTe2 achieves indirect to direct band gap transition.These results will open up new opportunities for their application in nanoelectronic devices.Secondly,we use Graphene and PtSe₂ as the metal electrode and channel material to build the hetero-multilayer and study their Schottky barriers.The n-type Schottky contact is formed and its barrier height is robust to the number of Graphene layer.Moreover,the gate-voltage can effectively induce the Schottky barrier transformation from n-type to p-type and contact type transformation from Schottky to Ohmic in the PtSe₂/Graphene hetero-multilayer.In addition,the n-type Schottky barrier height of Graphene/PtSe₂/Graphene is insensitive to the external electric field.While the band gap of Bernal PtSe₂/Graphene/Graphene exhibit modulation under external electric field.These results will provide meanful guideline to construct high preformance field effect transistor.Finally,we construct hetero-multilayers by combining the PtSe₂ and BN layers,forming the type-I band alignment.Both the conduction bottom band and valence top band are contributed by PtSe2.The electric field can effectively modulate the band gap and easily induce the type-I-to-type-II band alignment transition for BN/PtSe₂ hetero-multilayer.Furthermore,when the interlayer distance is compressed,the band gap of BN/PtSe2/Graphene hetero-trilayers can be obviously enlarged.The external electric field can easily induce the transition from n-type to p-type Schottky contact and until Ohmic contact in Gr/BN/PtSe₂hetero-trilayers.These results will be useful to guide the design of PtSe2-based electronic devices applications.