1. Department of Physics & Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu 603 203, India
2. Smart Energy & Nanophotonics R&D Group, Korea Institute of Industrial Technology, Gwangju 61012, Republic of Korea
3. Department of Semiconductor Science and Technology, Semiconductor Physics Research Center, Chonbuk National University, Jeonju 54896, Republic of Korea