1. Department of Physics, King’s College London, Strand, London, WC2R 2LS, United Kingdom
2. School of Electrical and Electronic Engineering,
Luminous! Center of Excellence for Semiconductor Lighting and Displays, Nanyang Technological University, Nanyang Avenue, Singapore 639798, Singapore
3. College
of Physics Science and Technology, Shenzhen University, Shenzhen 518060, China
4. Department of Electrical
and Electronics Engineering, Department of Physics, and UNAM-National
Nanotechnology Research Center, Bilkent University, Bilkent, Ankara 06800, Turkey