Design And Transport Characteristics Regulation Of Low-Dimensional Graphene-Like Nanomaterials Functional Devices

Since the 20th century,there have been many significant discoveries and inventions in the history of human science and technology development,among which the most famous is the integrated circuit chip,the cornerstone of modern information technology.However,the development of Moore’s law is getting slower and slower,and it has reached a bottleneck stage at present.The existing microelectronic processing technology is approaching the development limit.When the traditional silicon-based chip reaches below 5nm,quantum tunneling effect will appear,and when the process breaks through 1nm,quantum tunneling effect will lead to"electron runaway",resulting in chip failure.In this case,it becomes one of the feasible ways to further develop the chip to find the material to replace the silicon substrate.The emergence of new materials may change the status quo of the development of Moore’s Law,which is expected to usher in an inflection point.With the increasing need for miniaturization of electronic devices in recent years,researchers believe that graphene-like nanodevices are the most likely to solve the bottleneck of miniaturization development of electronic devices.Therefore,it is a key challenge to design and research new two-dimensional nanomaterials and realize the application of small size,high performance and low power consumption nanoelectronic devices.Based on the above situation,three graphene-like nanomaterials,tetra-penta-octagonal graphene（TPO-graphene）,biphenylene network graphene（BPN-graphene）and transition metal chalcogenides,are studied in this paper.This paper carries out systematic research on device design,structure optimization and physical property regulation of new materials,as well as related functional evaluation of devices:（1）Modulation of electrical performance of zigzag edged tetra-penta-octagonal graphene nanoribbons（TPO-ZGNRs）based devices via boundary passivations.TPO-ZGNRs were passivated with H,2H,O,OH,and Cl on the edge to produce TPO-ZGNRs-X（X=H,2H,O,OH,and Cl）.TPO-ZGNRs-H exhibits metallic properties regardless of the nanoribbon width and exists in the non-magnetic state.Although TPO-ZGNRs-OH and TPO-ZGNRs-Cl remain metallic,TPO-ZGNRs-2H and TPO-ZGNRs-O are semiconductors.In addition,the current–voltage curves of three TPO-ZGNRs-X（X=H,OH,and Cl）heterostructures device models contain a negative differential resistance region.Notably,the heterostructures device model in which TPO-ZGNRs are passivated with H and O atoms at different edge regions has negative differential resistance and rectification characteristics.This study is expected to facilitate the development of new carbon materials.（2）The surface activity of BPN is activated by adsorption of transition metals Co,V,W and Zr on BPN using the first-principles calculation method,so as to improve the adsorption properties of BPN on H₂S,SO₂,SO₂F₂and SOF₂gases,such as the increase of adsorption energy,charge transfer ability and gold properties.Nano-devices based on BPN-Co/V/W/Zr are proposed for adsorption of H₂S and SO₂gases.Their electron transport properties are revealed by density functional theory combined with non-equilibrium Green’s function method.Nanodevices based on BPN-Co/V/W/Zr show obvious electron transport anisotropy in the direction of Z-shape and armchair.The gas sensitivities of BPN-Co/V/W/Zr to H₂S and SO₂in armchair direction are 0.92and 0.54,respectively.These results indicate that BPN is a multifunctional material,which can regulate its electronic,transport and gas-sensitive properties by adsorbing transition metals Co,V,W and Zr,and has potential applications in electronic anisotropy and gas sensor components.（3）The six different stacked structures of the WS₂/WSe₂and WSe₂/WTe₂van der Waals heterostructures have very small and negligible effects on their electronic properties.The electronic properties of the WS₂/WSe₂and WSe₂/WTe₂heterostructures can be effectively regulated by biaxial strain.The WS₂/WSe₂and WSe₂/WTe₂heterostructures are type-II band alignments,which are suitable for optoelectronic applications.Moreover,both tensile strain and compressive strain can effectively regulate the optical properties of WS₂/WSe₂heterostructure,such as the peak and range of optical absorption coefficient.These good optical properties are conducive to the application of the WS₂/WSe₂heterostructures in optoelectronic devices.Therefore,the photoelectric characteristics of three kinds of photoelectric devices for zigzag and armchair types（Z-type and A-type）based on the WS₂/WSe₂heterostructures are studied,named PIN-junction,PIP-junction and NIN-junction photoelectric devices.The photoelectric properties of the A-type WS₂/WSe₂heterostructure are better than those of the Z-type.Our results suggest that the WS₂/WSe₂and WSe₂/WTe₂heterostructures are possible to make photodetector,and the strain can regulate the electronic and optical properties of the heterostructures,which have potential applications in photoelectric and other fields.To sum up,this paper focuses on the design of functional devices and the regulation of transport characteristics of low-dimensional graphene nanomaterials,which are mainly TPO-graphene,BPN-graphene and transition metal chiogenides.A variety of low-dimensional graphene nanomaterials functional devices with good negative differential resistance effect,rectification effect,gas sensitive properties and photoelectric properties are designed and studied.It is expected to be applied to the electronic,gas-sensitive and photoelectric fields in the future,which will help alleviate the bottleneck of the development of Moore’s law in the material industry.