1. Department of Electrical and Electronics Engineering, Department of Physics, UNAM--Institute of Materials Science and Nanotechnology and the National Nanotechnology Research Center, Bilkent University, Ankara, 06800, Turkey
2. Inorganic Material Laboratory, Material Research Center, Samsung Advanced Institute of Technology, Samsung Electronics Co., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, South Korea
3. SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
4. Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, and School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore