Fabrication And Physical Properties Of Two-Dimensional Material: Antimonene And PtSe₂

With the development of electronic industry and the improvement of the integration,the dimensions of electronic devices need to be further reduced.Therefore,during the process of exploring new materials,the dimensions and dimensions of electronic materials are also reduced.Since the successful preparation of graphene in 2004,two dimensional materials have attracted much more attention.The excellent properties of graphene,such as high thermal conductivity and high carrier mobility,makes graphene having a wide range of potential applications in future electronics,and also encourage people to explore more excellent properties of two-dimensional materials.In recent years,graphene-like materials（two-dimensional atomic crystal materials with single element such as silicene,germanene etc.）and two layered transition metal chalcogenides（TMDs,such as Mo S2）,has become a research hot topic in material science and received extensive attention with its excellent physical and chemical properties.In this paper,we focus on the study of antimonene,a new type of graphenelike two-dimensional atomic crystals,and PtSe₂,a new type of two layered transition metal chalcogenides.We study on their physical properties and structure characteristics with MBE,LEED,STM,SP-STM,XPS and other characterization methods combined with the first principle calculation.（1）Following the preparation of silicene,germanene and hafnene,antimonene--a new type of two-dimensional atomic crystals were predicted with excellent properties in optoelectronics and spintronics,and has attracted great attention.In the first part of this paper,we give the introduction about the preparation of monolayer antimonene on Pd Te2 with MBE.We chose Pd Te2 as the substrate to reduce the lattice mismatch between the substrate and the antimonene as much as possible.In the process of growth,we deposited high purity antimony on to the substrate while annealing the substrate.By the in-situ scanning tunneling microscopy and low energy electron diffraction,we observed that the growth of antimony（1 x 1）on the Pd Te2 surface,and the atomic resolution image of the antimonene honeycomb structure.At the same time,by using the X ray photoelectron spectroscopy and the first principles calculation,the twodimensional atomic structure of antimonene and weak interaction with the substrate are revealed.Furthermore,we have detected the chemical stability of antimonene in air by using STM and XPS measurements,and revealed the great potential of antimonene in future applications.（2）One dimensional structure in two-dimensional materials,such as the edges and nanoribbons have been a research hot topic.The experimental work about magnetic properties of a two-dimensional material edge is rare while there are a huge number of theoretical work on this field.In the second part of this thesis,we show the results of detecting the spin structure of the edges in PtSe₂ nanoribbon with the spin polarized scanning tunneling microscopy.By using the method of direct selenium,we grew the PtSe₂ nanoribbons on Pt（111）substrate.Using scanning tunneling microscopy combined with first principles calculations,we are able to determine the configuration of the nanoribbons.At the same time,the energy band bending in real space at the edge is studied by the scanning tunneling microscopy.Further,we performed the spin polarized scanning tunneling microscopy experiments in the opposite magnetic field with Ni tip and observed different signal on the different edge in the spectrum and mapping.Combined with contrast experiments using spin average scanning tunneling microscope,we observed spin structure of PtSe₂ edges for the first time.The experimental results will be of great value in the study of the two-dimensional material edge.（3）As a new type of transition metal chalcogenide material,the PtSe₂ has become a new hot topic in recent years due to its single layer has high mobility and wide band gap.In the third part of this thesis,we mainly focus on the growth of single layer and double layer PtSe₂ on HOPG,and the measurement of the intrinsic energy gap at PtSe₂ surface and edges.Using the MBE,we successfully prepared monolayer and bilayer PtSe₂ islands on graphite.The intrinsic energy gap of single layer and double layer PtSe₂ was measured for the first time by using low temperature scanning tunneling spectroscopy.At the same time,we also measured the distribution of energy gap at the edge of single layer,and revealed the phenomenon of band bending at the edge.Furthermore,we measured the energy gap distribution at the interface between the single layer and the double layer.With the first principle calculation,successfully reveals the effect on the gap from the interaction between layers and reveals the difference between PtSe₂ and other TMD material such as Mo S2.