1. Department of Physics; National Taiwan University; Taipei 106 Taiwan
2. Graduate Institute of Applied Physics; National Taiwan University; Taipei 106 Taiwan
3. Department of Materials Science and Engineering; National Taiwan University; Taipei 106 Taiwan
4. Institute of Optoelectronics Sciences; National Taiwan Ocean University; Keelung City 202 Taiwan
5. Center for Emerging Material and Advanced Devices; National Taiwan University; Taipei 106 Taiwan