Theoretical Investigation On The Properties Of Monolayer Tl₂O And C₃N-metal Interface And Bilayer Silicane Transistor

Two-dimensional（2D）semiconductors have attracted a lot of attention due to their fascinating physical properties and broad applications in the field of nanoelectronics.Due to its high carrier transport capacity,the absence of dangling bonds at the interface to reduce surface scattering,and the significant gate electrostatics generated by the atomic thickness,2D semiconductors are expected to be the channel materials for the next generation of semiconductor electronic devices.However,the 2D semiconductor is often directly in contact with the metal to inject the carrier,due to the lack of reliable doping means in the actual 2D semiconductor transistor.So that the Schottky barrier is often formed at the interface between the metal and the semiconductor,and the Schottky barrier impedes the transmission of carriers.So,forming low resistance electronic contacts is a great challenge for transistor devices.It is difficult to measure the sub-10nm 2D transistors in experiments at present.It is timely and necessary to use quantum transport simulation calculation to study and predict the performance of 2D transistors.In this paper,a variety of 2D semiconductors（monolayer Tl₂O and C₃N）with suitable band gaps and high mobility are selected.First principles and quantum transport simulation methods are used to determine the Schottky barrier height and polarity at the transistor devices.For monolayer Tl₂O field effect transistors（FET）,the n-type Schottky contacts are formed when Ni,Au,Sc and Ti₂C are used as electrodes with the lateral electron barrier heights of 0.25,0.27,0.27 and 0.36 e V,respectively.The p-type Schottky contacts are formed when graphene is used as electrode with lateral hole Schottky barrier height of 0.10 e V.The required n-type ohmic contacts are formed when Tl and Ti₂C（OH）₂ are used as electrodes;the required p-type ohmic contact is formed when Ti₂CF₂ is used as electrodes.Monolayer C₃N FETs,2D metals（graphene,Ti₂C（OH/F）₂,Zr₂C（OH/F）₂）and bulk metals（Au,Ni,Pd,Pt）were selected as electrodes.The performance of transistors in zigzag and armchair directions are investigated,respectively.The polarity of the FET can be easily adjusted by adjusting the work function of the metal.For the vertical Schottky barrier,the ohmic contacts are formed for 2D and bulk metal electrodes in FET（except for Zr₂CF₂ metal）.For lateral Schottky barrier,all metals form ideal ohmic contact in the armchair direction.2D metals form ohmic contact in the zigzag direction.The quantum transport simulation method is still applicable to the calculation of SBH and polarity in other 2D semiconductor transistor structures,and can guide the selection of metal electrodes for experiments to achieve low resistance electronic contact.The performance limits of bilayer silicane FET are investigated by combining density functional theory with non-equilibrium Green’s function.The optimized n-type and p-type bilayer silicane transistors can meet or approach the requirements of low-power devices of ITRS in terms of on-state current until channel length is reduced to 5nm or even 3 nm,which can be used as a promising channel material for sub-10 nm transistors.It is believed that in the near future,under the continuous promotion of theoretical research,the advantages of two-dimensional semiconductor materials can be fully utilized to realize the wide application of high-performance transistors based on two-dimensional semiconductor materials.