1. Semiconductor
Lighting Technology Research and Development Center, Institute of
Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
2. Luminous!
Center of Excellence for Semiconductor Lighting and Displays, School
of Electrical and Electronic Engineering, Nanyang Technological University, 639798 Singapore
3. School
of Materials Science and Engineering, Center for Nano and Micro Mechanics
(CNMM), Tsinghua University, Beijing 100084, China