Modulation On Electronic Structure Of Two-Dimensional Borophene And Carbon Nitrides

Two-dimensional?2D?monolayer borophene and carbon nitrides have been successfully synthesized,whose uniqe atomic structures and electronic properties have attracted remarkable attention.The both structures of borophenes synthesized experimentally are metallic,while covalent networks of the carbon and nitrogen atoms as a new class of 2D materials show semiconducting electronic properties.Thanks to the long spin-relaxation time and long spin-diffusion length,borophene and carbon nitrides have potential application in spintronic devices.It is necessary to study the electronic structure and magnetic properties of these new 2D materials by atomic adsorption and interfacial recombination.In this dissertation,the electronic structure of 3d transition metal?Sc,Ti,V,Cr,Mn,Fe,Co,Ni,Cu,Zn?adsorbed borophene;borophene/g-C₂N interface;g-C₂N,g-C₃N and g-C₄N₃/?-Fe₂O₃?0001?interface are studied using density functional theory.The electronic properties of borophene adsorbed by 3d transition metal atoms are investigated.Cr and Mn adsorptions induce the magnetic moment.Sc,Ti,V,Co,Ni,Cu and Zn have little effect on borophene.Fe adsorption induces a non-magnetic semiconducting characteristic,whose gap opening and magnetic moment can be tailored by strain.The electronicproperties of borophene/g-C₂N interface are studied.The band structures of borophene and g-C₂N are preserved in borophene/g-C₂N interface,resulting in the n-type Schottkybarrier.Upon the external electric field,a transition from the n-type Schottky contact to Ohmic contact is induced.The electronic properties of g-C₂N/?-Fe₂O₃?0001?interface are studied by first-principles calculations.Spin polarization is induced in g-C₂N by contacting to?-Fe₂O₃?0001?.The different terminations of?-Fe₂O₃?0001?can switch the conductivity of g-C₂N from the n-to p-type.The O-and single Fe-terminated interfaces can induce the half-metallic characteristic in g-C₂N,whose half-metallic gap can be tailored by the interlayer distance.The electronic properties of g-C₃N and g-C₄N₃/O-terminated?-Fe₂O₃?0001?interface are calculated.The O-terminated?-Fe₂O₃?0001?provide the stable physisorption to g-C₃N and g-C₄N₃.The spin polarization in g-C₃N and spin channel reversal in g-C₄N₃ are induced by the interfacial magnetic proximity with the O-terminated?-Fe₂O₃?0001?.