| 학회 | 한국재료학회 |
| 학술대회 | 2007년 봄 (05/10 ~ 05/11, 무주리조트) |
| 권호 | 13권 1호 |
| 발표분야 | 전자재료 |
| 제목 | MOCVD를 이용한 InGaN/GaN 기반 발광다이오드 구조 제작과 발광다이오드에의 응용 |
| 초록 | Firstly, the effects of well protection layer (WPL) on the optical and crystal properties of InGaN/GaN multiple quantum well (MQW) will be addressed. The five-pair MQW, consisting of InGaN well grown at 750 oC and GaN barrier grown at 850 oC, was simply embedded between GaN cladding layer on sapphire(0001) substrate. While this dual-temperature MQW growth scheme seemed better suited to the GaN barrier quality, it exposed the volatile InGaN well to a higher temperature ambient upon ramping-up process to grow the barrier. In order to prevent the fragile well, a thin GaN WPL was coated subsequently on each well layer at the same temperature before the temperature ramping-up. Consequently, it was found that the WPL directly influenced indium composition and optical properties of the MQW. Indium composition was in fact increased, as was evident from x-ray diffraction experiments. In addition, photoluminescence measurements showed emission peak wavelength was increased from 464 nm to 520 nm. These results provide the proof evidence that the WPL effectively suppresses indium re-evaporation during the ramping-up time. Present study proposes that the WPL paves a new pathway to increase the wavelength of InGaN/GaN MQW. Secondly, multiwavelength emitting InGaN/GaN QWs formed on V-shaped GaN(1-101) microfacet will be reported. After a MOCVD of 2 μm thick GaN, SiO2 mask stripes were formed along GaN＜11-20＞ direction by a conventional photolithography. The period and opening of the stripes were 11 and 4 μm wide, respectively. Subsequent regrowth of GaN generated the V-shaped (1-101) microfacets along ＜11-20＞ direction. Finally, five-period InGaN/GaN multiple QWs were fabricated on these microfacets. The cross sectional observation in the＜11-20＞direction by SEM revealed the well-developed microfacets. Interestingly, cathodoluminescence (CL) spectra measured on the microfacets showed a continuous change in the luminescence peak positions. The CL peaks were shifted to a longer wavelength from 420 nm to 440 nm as the probing points went up. We believe that by controlling growth parameters and mask geometries, not only the overall difference between the peak positions can be further increased but also a desired wavelength can be produced. Present works thus propose the fabrication of a monolithic white light emitting diode without phosphors. |
| 저자 | 주진우1, 강은실1, 백종협2, 이인환1 |
| 소속 | 1전북대, 2한국광기술원 LED 소자팀 |
| 키워드 | GaN; MOCVD; MQW; LED |
