中文摘要：

本文采用高分辨透射电子显微技术对在Si衬底生长的GaN基多量子阱外延材料的位错特征、外延层与衬底的晶体取向关系及界面的结晶形态等微观结构进行了分析和研究。结果表明：Si衬底生长的GaN与衬底有一定的取向关系;材料在MQW附近的穿透位错密度达108 cm-2量级,且多数为刃型位错;样品A的多量子阱下方可见平行于界面方向的位错,本文认为这可能是由于AlN/Si界面上的SixNy形成的多孔形态促使外延层进行侧向生长,使位错在高温GaN层沿横向弯曲所致,这样可进一步降低穿过量子阱的位错密度,有利于提高材料质量。

英文摘要：

The microstructure of GaN layer grown on Si（111） substrate was characterized using transmission electron microscopy（TEM）.The results show that GaN is hexagonal（and single crystalline）,and that the orientation relationships are（0001）GaN//（111）Si,GaN// Si.The dislocation density reaches 108cm-2 in n-GaN layer near MQW of the two samples,the main of which are pure edge dislocations（=1/3〈1120〉）.Dislocation below the quantum well in sample A is found to be parallel to the interface between the buffer layer and extension.The nanometer-sized holes in a thin SixNy layer probably enhance lateral growth and then decrease the dislocation density through the quantum well.