1. Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
2. Department of Electronics Engineering, National Changhua University of Education, Changhua 50007, Taiwan
3. Graduate School of Semiconductor Materials and Devices Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
4. School of Electronics Engineering, Kyungpook National University, Daegu 41566, Republic of Korea