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在3英寸(1英寸=2.54 cm)SiC衬底上采用金属有机物化学气相沉积(MOCVD)法生长GaN外延材料。研究了AlN缓冲层的应变状态对GaN外延层应变状态和质量的影响。使用原子力显微镜和高分辨率X射线双晶衍射仪观察样品表面形貌,表征外延材料质量的变化,使用高分辨喇曼光谱仪观察外延材料应力的变化,提出了基于外延生长的应变变化模型。实验表明,GaN外延层的张应变随着AlN缓冲层应变状态的由压变张逐渐减小,随着GaN张应力的逐渐减小,GaN位错密度也大大减少,表面形貌也逐渐变好。
GaN epitaxial material was grown on a 3 inch (1 inch = 2.54 cm) SiC substrate by metal organic chemical vapor deposition (MOCVD). The effect of AlN buffer layer strain state on the strain state and quality of GaN epitaxial layer was investigated. Atomic force microscopy and high resolution X-ray double crystal diffractometer were used to observe the surface morphology of the samples and characterize the change of the quality of the epitaxial material. The change of stress in the epitaxial material was observed by high resolution Raman spectroscopy, and the strain change model based on epitaxial growth was proposed. The experimental results show that the tensile strain of GaN epitaxial layer decreases gradually with the strain of AlN buffer layer and the dislocation density of GaN decreases with the decrease of GaN tensile stress, .