1. Computer, Electrical and Mathematical Sciences and Engineering Division; King Abdullah University of Science and Technology; Thuwal 23955-6900 Kingdom of Saudi Arabia
2. Department of Materials Science and Engineering; National Tsing Hua University; Hsinchu 30013 Taiwan Republic of China
3. Physical Sciences and Engineering Division; King Abdullah University of Science and Technology; Thuwal 23955-6900 Kingdom of Saudi Arabia
4. Department of Electrical and Computer Engineering; National University of Singapore; Singapore 117576 Singapore
5. National Institute of Advanced Industrial Science and Technology (AIST); AIST Central 5 Tsukuba 305-8565 Japan