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采用金属有机物化学淀积技术在不同倾角(0°—0.3°)的蓝宝石衬底上外延n型GaN.通过原子力显微镜观察到n型GaN均呈台阶流生长模式,0.2°和0.3°倾角衬底的n型GaN表面台阶朝向相同、分布均匀,明显地看到在0°倾角衬底的n型GaN表面由台阶重构直接导致的台阶朝向随机分布、疏密不匀的形貌.电子背散射分析表明,在0°倾角衬底的n型GaN外延层的应力随外延厚度增加而增加,而0.2°和0.3°倾角衬底的n型GaN外延层的应力没有明显的变化.电学和光学特性研究表明,0.2°和0.3°倾角衬底的n型GaN有较高的电子浓度和较低的黄光带与近带边强度之比.
The n-type GaN was epitaxially grown on a sapphire substrate with different tilt angles (0 ° -0.3 °) by metal organic chemical deposition. The n-type GaN was observed by atomic force microscopy with a stepped flow growth mode, a 0.2 ° and 0.3 ° tilt substrate Of the n-type GaN surface with the same orientation and uniform distribution, it is obvious that the step-wise random distribution and sparse unevenness of the surface of the n-type GaN on the 0 ° dip substrate are directly caused by the step reconstruction. The analysis shows that the stress of n-type GaN epitaxial layer at 0 ° tilt substrate increases with the increase of epitaxial thickness, while the stress of n-type GaN epitaxial layer at 0.2 ° and 0.3 ° tilt substrate has no obvious change. The results show that the n-type GaN with 0.2 ° and 0.3 ° tilt substrates has higher electron concentration and lower ratio of yellow band to near band edge.