| 학회 | 한국재료학회 |
| 학술대회 | 2007년 가을 (11/02 ~ 11/02, 성균관대학교) |
| 권호 | 13권 2호 |
| 발표분야 | 반도체재료 |
| 제목 | Ag/AgAl ohmic reflector for high-performance near-UV GaN-based flip chip light emitting diodes |
| 초록 | GaN-based light emitting diodes(LEDs) having large output power is essential for solid-state lightening. But conventional top-emitting LED structures suffer from heat disssipation and current crowding problem caused by substrate and semi-transparent current spreading layer. To improve this problem, flip-chip LEDs having reflector at a p-type electrode are introduced. Ag is known to be the good reflector, while Ag suffers from thermal degradation (agglomeration and formation of voids above 300℃). Such problems were solved by several method. For example, transparent conducting oxide interlayers were used between Ag and p-GaN to increase thermal stability of Ag contacts. In this work, we introduced Ag(200 nm)/AgAl(100 nm) ohmic contacts to p-type GaN for near-UV (405 nm) flip-chip LEDs. It is shown that the use of Ag/AgAl(8 at% Al) ohmic contacts results in better electrical and optical properties as compared to single Ag contacts when annealed at 430℃. For example, Ag/AgAl (8 at% Al) contacts give specific contact resistance of 4.6x10–4 Ωcm2 and reflectance of 90% at a wavelength of 405 nm. However, use of an AgAl (with 50 at% Al) layer is not effective. LEDs fabricated with the Ag/AgAl (8 at% Al) reflectors produce higher light output as compared with the ones with single Ag reflectors. Ohmic mechanisms of the Ag/AgAl contacts are described and discussed by Auger electron spectroscopy(AES). |
| 저자 | 김윤한1, 황윤태2, 홍현기1, 나현석1, 오준호1, 김강원1, 전준우1, 김용현1, 윤주헌1, 성태연1 |
| 소속 | 1고려대, 2Univ. of California at Santabarbara |
| 키워드 | GaN flip-chip light-emitting diode; AgAl reflector; Ohmic contact |
