1. Department of Electronic Material Engineering Korea Maritime and Ocean University; Busan 49112 Korea
2. Compound Semiconductor Fabrication Technology Center Korea Maritime and Ocean University; Busan 49112 Korea
3. LED-Marine Convergence Technology R&BD Center Pukyong National University; Busan 48513 Korea
4. Department of Electrical and Electronics Engineering Aichi Institute of Technology; Toyota Aichi 470-0392 Japan
5. Department of Physics Andong National University; Andong 36729 Korea