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Local Analysis of the Complex Structures and the Ge Chemisorption Process on Si (111)-7X7 Surface (B.S. thesis)
Beijing Laboratory of Vacuum Physics, Institute of Physics, Chinese Academy of Sciences
Abstract:
Based on an environmental-dependent tight-binding potential, we present a theoretical study of formation process of the complex structures on Si(111)-7X7 surface. Mechanism of manipulation of atoms on Si(111)-7X7 surface and self-assembly nano-structures are analyzed with scanning tunneling microscopy.
We propose the site-specific binding energies (SSEB's) to analyze the binding properties of surface atoms and show that they can reflect the relative desorption energies of different adatoms very well. By the calculation of the localized density of states on various surface sites, we summarize the information contained in the electronic band structure E(k) of the crystal.
Furthermore we studied the self-organized growth of submonolayer Ge on Si(111)-7X7 surface. At very low concentration the reverse of LDOS of the substitutional Ge atoms on the Si surface can be observed at various bias voltages. So the positions of Ge atoms in the Si Surface can be identified with STM by the good differentiation between Si atoms and Ge atoms in proper imaging conditions. The formation mechanism of the self-organized structure is discussed.

Measurement for the Thermal Conductivity with Flash Method
Measurement for the Modulus of Elasticity with a CCD camera
General Physics Laboratory & Shichuang New Technology Corporation, Peking University

Gradiometer of High Tc rf SQUID for Magnetocardiography(MCG) Measurement
State Key Laboratory for Artificial Microstructure & Mesoscopic Physics, Peking University

Measurement for Optical Parameters of Thin GaN Film
General Physics Laboratory, Peking University