Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong;
State Key Laboratory of silicon Materials, Zhejiang University, Hangzhou 310027;
Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong;
State Key Laboratory of silicon Materials, Zhejiang University, Hangzhou 310027;
Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601, USA;
Department of Physics, Kansas State University, Manhattan, Kansas 66506-2601, USA;