非极性a面p型AlGaN/GaN超晶格MOCVD生长及特性表征

MOCVD Growth and Characterization of Nonpolar a-Plane p-Type AlGaN/GaN Superlattices

利用铟(In)表面活性剂辅助Mg-δ掺杂技术和金属有机化学气相沉积(MOCVD)技术,在r面蓝宝石衬底上成功生长了高空穴浓度的非极性a面p型Al0.6Ga0.4N/GaN超晶格样品。分别使用扫描电子显微镜(SEM)和原子力显微镜(AFM)分析了生长的超晶格样品的表面形貌,并使用霍尔效应测试系统在室温下测量了经过电极制作和空气氛围退火处理的超晶格样品的空穴浓度和空穴迁移率。研究结果表明,在MOCVD生长过程中精心优化TMIn摩尔流量可以使该超晶格样品表面的均方根(RMS)粗糙度降低21.4%,同时其空穴浓度增加183.3%。因此,适量地引入In表面活性剂不仅可以明显改善非极性a面p型Al0.6Ga0.4N/GaN超晶格样品的表面形貌,而且能显著增强样品的空穴浓度。

The nonpolar a-plane p-type Al0.6Ga0.4N/GaN superlattice sample with high hole concentration was successfully grown on r-plane sapphire substrate by adopting In-surfactant-assisted Mg-δdoping technology and metal organic chemical vapor deposition(MOCVD)technology.The surface morphology of the superlattice sample was analyzed by the scanning electron microscope(SEM)and atomic force microscope(AFM),respectively.Moreover,the hole concentration and hole mobility of the superlattice sample treated by electrode fabrication and thermal annealing in the air ambient were measured by using the Hall effect measurement system at room temperature.The research results show that due to the careful optimization of the TMIn mole flow rate in the MOCVD growth process,the root-mean-square(RMS)roughness of the nonpolar a-plane p-type Al0.6Ga0.4N/GaN superlattice sample decreases by 21.4%and the hole concentration increases by 183.3%.Thus,both the surface morphology and the hole concentration of the nonpolar a-plane p-type Al0.6Ga0.4N/GaN superlattice sample are improved significantly with the proper usage of In-surfactant.