| 학회 | 한국재료학회 |
| 학술대회 | 2004년 봄 (05/14 ~ 05/14, 강릉대학교) |
| 권호 | 10권 1호 |
| 발표분야 | 반도체 II (화합물) |
| 제목 | 유기금속 화학기상 증착법을 이용한 높은 조성의 자발 형성 InGaN 양자점의 성장 |
| 초록 | Nitride quantum dots (QDs) are expected to provide the artificial carrier localization centers to enhance the emission efficiency of active layers with negligible compositional fluctuation. In-rich InGaN is supposed to be more favorable to form 3-dimensional structures than Ga-rich InGaN due to the much larger lattice mismatch between InGaN and substrates. In addition, according to recent report, the band gap of InN is generally accepted as 0.7 eV. In this case small change of dot height or In composition would cause the large shift of emission wavelength. In this work, we report our experimental results on the growth of In-rich InGaN QDs. The size and density of InGaN QDs could be controlled by changing growth conditions. We could enhance the optical properties of QDs and control the emission wavelength of InGaN QD. After 2 µm GaN was grown on sapphire at 1080 oC by low-pressure metalorganic chemical vapor deposition (LP-MOCVD), InGaN QDs were performed changing the growth temperature from 640 to 760 oC. To obtain the photoluminescence spectra, GaN capping layer was grown on these InGaN QDs at the same temperature. Several growth parameters, such as growth temperature, growth time, and input flow rates of TMIn, were changed to control structural and optical properties of InGaN QDs. Samples were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), temperature dependent photoluminescence (TD - PL), and stimulated emission (SE) by optical pumping. Surface morphology of In-rich InGaN QDs was examined by AFM. At first, QDs were formed non-uniform consisting of large QDs and small QDs, as growth time decreased, uniform QDs without large QDs were formed. On the other hand, when growth time increased to 8 sec., the size of large QDs increased maintaining size of small QDs. It is suggested that large QDs were fromed by coalescence of small QDs. We were also obtained uniform QDs with high density of 5.1x1010 cm-2 by adjusting growth parameters and introducing AlGaN buffer layer. Typically, In-rich InGaN QDs were found to have relatively low aspect ratio (height/diameter) by TEM and AFM. It is very similar to that of InN QDs recently reported [1], however, quite different from that of typical Ga-rich InGaN QDs [2]. Optical properties of QDs were investigated using TD-PL and SE. Strong emission peak from InGaN QDs was observed at 3.1 eV even at room temperature. Stimulated emission peaks could be observed at 3.27 eV. The effect of AlGaN on the formation of In-rich InGaN will be addressed. [1] O. Briot, B. Maleyre, and S. Ruffenach, Appl. Phys. Lett., 83, 2919 (2003). [2] K. Tachibana, T.Someva, and Y. Arakawa, Appl. Phys. Lett., 74, 383 (1999). |
| 저자 | Hee Jin Kim1, Hyunseok Na1, Yoori Shin1, Soon-Yong Kwon1, Keon-Hun Lee1, Dong-Hyuk Kim1, Ho-Sang Kwack2, Ji-Young Kim2, Yong Hoon Cho2, Euijoon Yoon1 |
| 소속 | 1Seoul National Univ., 2Chungbuk National Univ. |
| 키워드 | In-rich InGaN; quantum dots; QDs; MOCVD |
