Theoretical Study Of Electrical Transport Characteristics Based On WS₂/two-dimensional Metal Van Der Waals Heterojunction

The emergence of graphene has set off an upsurge in people's research on new materials.Two-dimensional(2D)materials have been discovered or synthesized by scientists from various countries,such as black phosphorus(BP),boron nitride(BN),transition metal carbide(TMC),transition metal disulfide(TMD),etc.Both WS₂ and MoS₂ are typical two-dimensional materials with a certain band gap in the energy band,which can replace traditional three-dimensional semiconductors.In practical applications,many factors will affect the performance of the device.For example,when a 2D semiconductor is in contact with an electrode,a Schottky barrier is formed,which has an adverse effect on the prepared electronic device;when a 2D semiconductor is in contact with an electrode,a tunneling barrier is generated,which is also an important factor hindering the practical application of the device.In order to solve the above problems,this paper uses first-principles calculations to analyze in detail the contact properties of heterojunctions formed by different electrode materials and WS₂,the electrical transport characteristics of the two-electrode system based on WS₂,and the study of 1T'/2H MoS₂heterogeneous junction contact nature has been effectively controlled.The specific research content is as follows:1.Based on the above-mentioned problems when the 2D semiconductor is in contact with the electrode,a study on the formation of a van der Waals heterojunction between Graphene/M₃C₂(M=Cd,Hg,Zn)and 2D WS₂ has been carried out.The first-principles calculation method is used to study the contact properties of the van der Waals heterojunction formed with 2D WS₂ when Graphene/M₃C₂ is used as an electrode.When WS₂/graphene forms a van der Waals heterojunction,the inherent properties of the two materials can be well maintained;a mixed state appears at the Fermi level of the M₃C₂/WS₂ van der Waals heterojunction,which affects the inherent properties of the material.Graphene/M₃C₂ and WS₂ formed an n-type Schottky contact.The Zn₃C₂/WS₂ two-electrode system was evaluated and the system formed an n-type contact.The above research provides theoretical guidance for the production of n-type WS₂ semiconductor devices.2.Based on the above research results,there is a problem of large contact barriers,and the use of metallic transition metal disulfide XA₂(X=V,Nb,Ta;A=S,Se)and two-dimensional WS₂ to form a van der Waals heterojunction Research.The study found that the WS₂/XA₂ van der Waals heterojunction can well maintain the inherent properties of the two materials.XA₂ and WS₂ formed a p-type Schottky contact.Interestingly,when VSe₂ was selected as the electrode,the two-electrode system was evaluated as an n-type contact.When VS₂,NbS₂ and TaS₂ were used as electrodes,the carrier polarity didn't change,and the evaluation of the two-electrode system was still p-type contact.In the calculation of electrical transport,the Schottky barrier(SBH)of all systems has obviously increased.This research effectively reduces the Schottky barrier and provides a theoretical idea for the preparation of p-type WS₂ semiconductor devices.3.Based on the heterogeneity of the two-dimensional material,the research on the contact properties of the 1T'/2H MoS₂ heterogeneous junction was carried out.It is found that the interface barrier of the heterogeneous junction is not uniform,and the local potential of the interface is lower than the barrier of the interlayer gap,and the appearance of these regions provides a path for electron transmission.The Schottky barrier of the1T'/2H MoS₂ heterogeneous junction contact interface can be adjusted by adsorbing a variety of metallic atoms or applying stress.Both methods can transform Schottky contacts into ohmic contacts,and applying stress can broaden the area below the average barrier.The area of the average barrier area.This study calculated the two main potential barriers affecting the 1T'/2H MoS₂ heterogeneous junction,and successfully controlled them,providing a theoretical reference for the actual control of material contact barriers.