1. Department of Materials Science and EngineeringFaculty of Science and TechnologyMeijo University Nagoya Aichi 468-8502 Japan
2. Research & Development DepartmentKoito Manufacturing Co., Ltd. Shizuoka 424-8764 Japan
3. Optoelectronics DepartmentTOYODA GOSEI Co., Ltd. Inazawa Aichi 492-8542 Japan
4. Akasaki Research CenterNagoya University Nagoya Aichi 464-8603 Japan