Abstract
The emergence of topological insulators and nano-material brings the importance of surface science to a new level. The properties of topological insulator depend strongly on surface state. The novel properties of nano-material strictly relates to its surfaces structure due to the large surface-area-to-volume ratio. In this talk, The surface morphology of the Bi2Se3(111)-(2x2) reconstruction and the ZnO nano-rods are discussed by the virtue of low energy electron diffraction(LEED).
Bi2Se3(111)-(2x2) was prepared by molecular beam epitaxy, an atomic model with Se on the top site is proposed by the virtue of multiple incidence angles LEED IV Patterson inversion. Well aligned ZnO nano-rods array were prepared by vapour phase transport growth. LEED results suggest the nano-rods undergo different extent of relaxation comparing to that of single crystal. The side facet of ZnO nano-rods and the hydrothermal growing method of well aligned ZnO nano-rod are also covered. Here, we emphasise this is the first ever successful extraction of LEED IV from free standing nano-material surfaces.
Although the above proved LEED is a powerful technique in surface morphology analysis, conventional LEED optics suffers electric charge up when probing insulating material. In order to bring LEED to its widest potential, microchannel plate low energy electron diffraction (MCP-LEED) system was implemented. An automate LEED data acquisition scheme was installed on the MCP-LEED system. The capability of MCP-LEED is justified. Pro and cons, as well as suggested future improvements of MCP-LEED are discussed.