a
Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, P. R. China
E-mail: wmliu@mail.ipc.ac.cn
;
Tel: +010-82543435
b
Center of Super-Diamond and Advanced Films (COSDAF) and Department of Physics and Materials Sciences, City University of Hong Kong, Hong Kong, P. R. China
c
Graduate School of the Chinese Academy of Sciences, Beijing, China