侧向外延生长GaN的结构特性(英文)

Structural Properties of Laterally Overgrown GaN

研究了在刻有图形的GaN“衬底”上用HVPE方法侧向外延生长 (ELO)GaN的结构特性。在SiO2 衬底上侧向外延生长GaN已经实现 ,并得到了平面的ELOGaN薄膜。采用扫描电子显微镜、透射电微镜和原子力显微镜技术研究了这种ELOGaN材料的结构和表面形貌。原子力显微镜图像表明 :在ELO范围中的4 μm2 面积上不存在明显的阶状形貌。透射电子显微镜的观测表明在ELO范围内位错密度很低。在接合的界面上没观察到有空隙存在。但观测到晶格的弯曲高达 3 3°,这被归因为由GaN层下的“籽层”和接合界面处的水平倾料和猝灭所产生的螺旋位错的积聚。

Structural properties of epitaxially laterally overgrown (ELO) GaN on patterned GaN "substrates" by hydride vapor phase epitaxy (HVPE) have been investigated. T he epitaxially lateral overgrowth of GaN on SiO 2 areas is realized and a plana r ELO GaN film is obtained. Scanning electron microscope, transmission electron microscope (TEM) and atomic force microscope (AFM) are used to study the structu re and surface morphology of the ELO GaN materials. AFM images indicate that no observable step termination is detected over a 4μm 2 area in the ELO regio n. T EM observations indicate that the dislocation density is very low in the ELO reg ion. No void at the coalescence interface is observed. Lattice bending as high as 3 3° is observed and attributed to pileup of threading dislocations coming fro m the underlying GaN "seeding layer" and tilting horizontally and quenching at the coalescence interface.