Effect of Ga to N flux ratio on the GaN surface morphologies grown by plasma-assisted molecular-beam epitaxy

• Main Authors: Yao-i Chang, 張燿一
• Other Authors: Ikai Lo
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/s5r637

碩士 === 國立中山大學 === 物理學系研究所 === 95 === We mainly studied the morphology of GaN structures which were grown by plasma-assisted molecular beam epitaxy. The only condition we changed is Ga/N Ratio. Based on observation of reflection high energy electron diffraction (RHEED) patterns, we found all samples belong to two-dimensional (2D) growth mode. Also, based on scanning electron microscope (SEM) analysis, we found when Ga/N Ratio is 0.13 and 0.18, the surface of sample will be smoothest. Furthermore, based on the roughness result derived from atomic force microscope (AFM), we got the same result. Then we observed the surface of samples after etching, we found all samples belong to Ga-face. Also, we can detect the degree of the state of mismatch under X-ray diffraction analysis. We found when Ga/N Ratio is 0.13, we got the lowest screw dislocation density; and when Ga/N Ratio is 0.18, we got the lowest overall dislocation density. In conclusion, we are trying to find sample growing parameters which could generate both better morphology and better structure.