Dislocation classification of a large-area β-Ga2O3 single crystal via contrast analysis of affine-transformed X-ray topographs

Abstract

X-ray topography (XRT) was performed on a (2¯01)-oriented β-Ga2O3 substrate using various diffraction vectors (g-vectors). The defect-related contrasts could be grouped roughly into line, dot, and rod contrasts based on their shapes. Most line contrasts were caused by screw-type dislocations that extended in the 〈010〉 direction in the (2¯01) plane. The dot contrasts were attributed to dislocations that had outcrops on the (2¯01) surface, while the rod contrasts were attributed to three-dimensional defects. To analyze how the contrast of a given dislocation varied across topographs taken with different g-vectors, affine transformation was applied to correct image deformations caused by differing projection angles and precisely aligned dislocation coordinates were obtained for all images. This enabled us to perform statistical contrast analyses on a large number of dislocations. The results indicated the presence of several typical Burgers vectors, including 〈010〉, 〈001〉, 〈100〉, and 〈101¯〉. A large proportion of dislocations exhibited small Burgers vectors.