STM Study Of Two-dimensional Structures Fabricated On Copper And Copper Oxide

Low-dimensional materials,for its high surface area and special bonding and geometric structures,has extra-ordinary chemical,physical and electronic properties.The discovery of mechanically exfoliated graphene in 2004 resulted in a new explosion of interest in two-dimensional(2D)nanostructures.Among 2D nanostructures,2D antimony structures,especially antimonene,have gotten attention because of the high stability and wide bandgap.In this dissertation,the 2D antimony structures are prepared on oxide layer of Cu(111)and Cu(110)surfaces.And the copper selenide are prepared on Cu(111)to explore the structure features different from typical transition metal dichalcogenides(TMDs).The main contents are as follows.The epitaxial growths of antimony structural phases on oxide layer of Cu(111)are systemically studied by scanning tunneling microscopy(STM).The oxidation of Cu(111)forms a corrugated oxide layer structure with forty-one times the unit cell area of Cu(111).The initial deposition of Sb atoms gives rise to the formation of flat(?7×?7)-Sb.The density functional theory(DFT)calculations figure out the structure of(?7×?7)-Sb phase.The further deposition forms buckled antimonene phases.Finally,a flower-like antimony nanoring configuration has been observed and shows high stabilities for oxygen exposure.The scanning tunneling spectroscopy measurements show that the(?7×?7)phase exhibits metallic property,and the antimonene and nanoring phases both show semiconducting features.The well-aligned armchair-like and zigzag nanostructures of antimony prepared by epitaxial growth on the copper oxide layer of Cu(110)are systemically studied.The oxidation of Cu(110)forms c(6×2)and(2×1)structure.The deposition of Sb atoms on c(6×2)forms armchair-like nanostructure,and the initial c(6×2)configuration changes into the(2×1)structure.By combining STM experiments with DFT calculations,the structure of armchair phase is revealed.With the Sb coverage increasing,two metastable intermediate phases and c(2×2)configuration appear.Further deposition of Sb atoms finally gives rise to the formation of zigzag nanostructure fabricated on surface of c(2×2).Three kinds of dislocations of zigzag nanostructure have been observed.Both well-aligned antimony nanostructures exhibit high stabilities.The scanning tunneling spectrum of each phase is measured,and the spectrum of armchair phase is consistent with the density of state calculated by DFT.Our results might provide a way for fabricating stable 2D materials with a well-defined edge structure on oxide surfaces.The method of epitaxy growth is employed to grow a single layered copper selenide structure on Cu(111).The surface morphology we have fabricated presents a planar honeycomb structure which is different from the typical TMDs.The lattice registry of CuSe with respect to the substrate Cu(111)causes a Moire pattern.Combined with density functional theory(DFT)calculation,the narrow band gap of CuSe structures is investigated in detail.