Physics Department,Shanghai University,Shanghai 200444,China;
Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences,Shanghai 200050,China;
School of Information Science and Technology,Shanghai Tech University,Shanghai 201210,China;
Department of Microtechnology and Nanoscience,Chalmers University of Technology,41296 Gothenburg,Sweden;
National Laboratory for Infrared Physics,Shanghai Institute of Technical Physics,Chinese Academy of Sciences,Shanghai 200083,China;
scanning tunneling microscopy; molecular beam epitaxy; semiconductor surface;