Identification of dislocation characteristics in Na-flux-grown GaN substrates using bright-field X-ray topography under multiple-diffraction conditions

Abstract

Basal-plane and threading dislocations in multipoint-seed Na-flux-grown GaN single crystals are characterized in terms of Burgers vectors mainly by using bright-field X-ray topography under multiple-diffraction conditions. The technique, combined with a CMOS camera system with high spatial resolution, can provide topographic images of the dislocations with a relatively high dislocation density (up to approximately 5×105cm−2). It is possible to directly determine the Burgers vector of individual dislocations based on invisibility criteria. From the present experiment, it is found that almost all basal-plane dislocations have a-type Burgers vectors, and threading dislocations have a- and (a + c)-type Burgers vectors.