CHARACTERIZATION OF DISLOCATIONS IN GAN BY TRANSMISSION ELECTRON-DIFFRACTION AND MICROSCOPY TECHNIQUES

A combination of transmission electron microscopy imaging and diffract ion techniques is used to characterize crystal defects in homoepitaxia l GaN thin films. The Burgers vectors of dislocations is established b y combining large-angle convergent beam electron diffraction and conve ntional diffraction contrast techniques. It is shown that dislocations with Burgers vectors c, a, and c+a are present. Evidence is presented that dislocation segments lying in the interfacial plane are dissocia ted on a fine scale. The significance of the observations for understa nding homoepitaxial growth of GaN is discussed. (C) 1996 American Inst itute of Physics.