Study On The Electron Transport Properties Of Planar Heterojunction Based On Carbon-based Two-dimensional Materials

Due to the quick development of modern science and technology,the development of information technology requires miniaturization of the size of electronic devices which creates more restrictions on the materials used to make devices.Through these efforts,the highly integrated electronic devices requirement can be done.Due to the unique properties in electronics and optics of two dimensional materials,two dimensional materials are widely used in nanoelectronic devices.Meanwhile,based on various two dimensional materials,many novel two dimensional heterojunctions have also been constructed.With the unique electronic characteristics of two dimensional heterojunctions,they have attracted widespread attention from researchers.Two dimensional heterojunctions can be divided into two categories:two dimensional vertical heterojunctions and two dimensional lateral heterojunctions.Since different materials form cohesive interfaces through covalent bonding,two dimensional lateral heterojunctions with excellent electron characteristics show potential application prospects in future semiconductor devices.Therefore,this paper uses the calculation software ATK to establish a transverse heterojunction model.Based on density functional theory and non-equilibrium Green's function method,the electronic structure and transport properties of three kinds of lateral heterojunctions are studied.It provides theoretical guidance for designing two dimensional lateral heterojunctions in experiment.Firstly,through constructing Graphene/MoS₂ heterojunctions with three different MoS₂lengths and two different interface structures,the current-voltage characteristics,the density of states,and the transmission spectra at the corresponding bias were calculated to study the effect of different interface structures.And the effect on the transport properties of Graphene/MoS₂ lateral heterojunctions by different MoS₂ lengths and different interface structures was also studied.The calculation results show that the electron transport characteristics of graphene/MoS₂ lateral heterojunctions are mainly affected by the length of MoS₂.By reducing MoS₂ length,the transport performance of the heterojunction can be significantly improved.And different interface structures lead to the difference in the output current of the heterojunction but not affect its change trend.In addition,all graphene/MoS₂ lateral heterojunctions exhibit good rectification and negative differential effects.Based on these characteristics,it provides guidance for the future design of the lateral heterojunction of other materials.Secondly,using graphyne and MoS₂ to construct two graphyne/MoS₂ and graphdiyne/MoS₂lateral heterojunctions.And we also study the effect of different graphyne structures and interface structures on electron transport performance of heterojunctions.The calculation results show that due to the difference in the number of acetylene bonds and the size of the lattice in the crystal structure of graphyne and graphdiyne,different strains are generated in the process of constructing the heterojunction.This causes the two heterojunctions to form different Schottky barriers in the interface region,which in turn affects their output characteristics.The results show that the lateral heterojunctions of different interface structures enrich the transport properties of graphynyne devices and promote more applications of graphyne in nanoelectronic devices.Finally,two different lattice configurations of graphane and graphene were combined to form a lateral heterojunction along the edges of the sawtooth and handrail,and the electronic structure and transport properties of the heterojunction were calculated.The effects of graphane with different edge structures and different configurations on the transport properties of graphene/graphane heterojunctions were investigated.The calculation results show that different edge structures make heterojunctions exhibit different electronic characteristics.By calculating its band structure and density of states,the zigzag type heterojunction exhibits metal characteristics and the handrail type heterojunction exhibits semiconductor characteristics,and its output characteristics are different,which can effectively regulate the electronic properties of the heterojunction.Different configurations of graphane cause the difference in the output value of the heterojunction.These characteristics provide more ideas for research in practical experiments.