Characterization of GaN/AlGaN heterostructures grown by molecular beam epitaxy

• Main Authors: Kuang-yao Chen, 陳光耀
• Other Authors: Ikai Lo
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/43551969848473107235

碩士 === 國立中山大學 === 物理學系研究所 === 93 === We mainly studied the characterization of GaN/AlGaN heterostructures which were grown by molecular beam epitaxy. For reduced lattice mismatch, we inserted AlN as buffer layer. We varied the parameters of buffer layer, such as the ratio of nitrogen and aluminum and the thickness. By the analysis of X-ray diffraction, we could determine the state of mismatch. For the thickness of buffer layer, lattice mismatch is most serious at 20 minute growth. Under the observation of field emission scan electron microscopy and reflection high energy electron diffraction, we found N/Al=40 is N-face and N/Al=26 is Ga-face. For the thickness of buffer layer, the samples of 1-minute and 5-minute growth had the optimal Ga-face. For the investigation of photoluminescence, we could obtain the energy gap of AlGaN is 3.42ev. Furthermore, the doping silicon was used to vary carrier concentration, and we could show that a good Hall mobility was achieved at the doping temperature 1250℃. We also could show good Hall mobility at 1 minute growth and 5 minute growth (N/Al=26). We tried to find the best parameters for the growth of GaN/AlGaN heterostructures.