| 학회 | 한국재료학회 |
| 학술대회 | 2015년 봄 (05/14 ~ 05/15, 구미코) |
| 권호 | 21권 1호 |
| 발표분야 | F. 광기능/디스플레이 재료 |
| 제목 | Improved thermal stability of Ti-based ohmic contact to N-polar n-type GaN for vertical light emitting diodes by Indium layer |
| 초록 | The fabrication of high-power and high-efficiency GaN-based light emitting diodes (LEDs) is needed for solid-state lighting applications. In this point of view, vertical LEDs (V-LEDs), which are fabricated via the removal of sapphire substrate for heat dissipation and light extraction efficiency, have been widely studied. The formation of thermally stable ohmic contacts to N-polar n-type GaN is essential for high performance V-LEDs. For n-type contacts, conventional LEDs are easily formed using Ti-based schemes, while V-LEDs are uneasy to form ohmic contacts to N-polar n-type GaN. Unlike n-ohmic contacts to Ga-polar n-type GaN, n-ohmic contacts to N-polar n-type GaN show poor electrical properties when annealed at temperatures below ~300 ℃. The thermal instability of n-ohmic contacts to N-polar n-type GaN at low temperatures was attributed to the formation of acceptor-like Ga vacancies near the N-polar n-type GaN surface region because of out-diffusion of Ga atoms. Thus, it is necessary to form thermally stable n-ohmic contacts to N-polar n-type GaN. In this work, we have investigated the electrical properties of a In/Ti/Al scheme so as to develop a thermally stable Ti-based n-ohmic contacts to N-polar n-type GaN. It is shown that the In/Ti/Al contacts produce better electrical characteristics than Ti/Al contacts and after annealing 300 ℃ in N2 ambient, In/Ti/Al contacts exhibit the lower specific resistance than Ti/Al contacts. |
| 저자 | 김성기, 성태연 |
| 소속 | 고려대 |
| 키워드 | Vertical light emitting diodes; Ohmic contacts; N-polar n-type GaN; Thermal stability |
