Different structural origins for different sized surface pits observed on a-plane GaN film  

作　　者：GAO ZhiYuan LI JiangJiang XUE XiaoWei CUI BiFeng XING YanHui ZOU DeShu 

机构地区：[1]Microelectronic School, Beijing University of Technology

出　　处：《Science China(Technological Sciences)》2016年第1期156-161,共6页中国科学（技术科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11204009&61204011);Beijing Municipal Natural Science Foundation(Grant No.4142005)

摘　　要：A correlation study between the observed surface morphology using high-resolution scanning electron microscopy(HRSEM) and the observed structural imperfections using transmission electron microscopy(TEM) has been conducted for a-plane Ga N. There are three different sized asymmetric surface pits: large pit of 500 nm–2 ?m in side length, medium pit of 50 nm in side length, and small pit with side lengths of less than 5 nm, which originate from incomplete island coalescence, screw dislocation, and partial dislocation(PD), respectively. Both screw dislocation and PD can produce pits on the free surface because they have a perpendicular line tension to the surface, which must remain in balance with the surface tension. The two types of dislocation lead to distinctive pit sizes because the PD has a smaller Burgers vector component along the dislocation line than the pure screw dislocation. A pit that is produced in the island-coalescing process is much larger than those caused by dislocations because island coalescence is a kinetic process that involves large-scale mass transportation, whereas the dislocation mediates the surface in the local area. These three types of surface pits sometimes interact with one another in space. The coalescence of the island determines the surface morphology at large scales, whereas the defects affect the details.

关 键 词：surface pits nonpolar Ga N screw dislocations partial dislocations Island coalescence 

分 类 号：TB383.2[一般工业技术—材料科学与工程]