Determination of Burgers-vector directions of threading edge dislocations in GaN by phase-contrast microscopy
Abstract
Phase-contrast microscopy enables rapid, nondestructive observation of threading dislocations in GaN, but the relationship between dislocation contrast and the Burgers vector has not been established. Here, we demonstrate that the in-plane Burgers-vector direction of threading edge dislocations in GaN can be determined from the arrangement of bright and dark contrast in phase-contrast microscopy images. The relationship was first established for threading edge dislocations in ammonothermal GaN whose Burgers vectors were independently determined by X-ray topography and was subsequently applied to hydride vapor phase epitaxy-grown GaN. The Burgers vector predicted from the phase contrast was verified by weak-beam dark-field TEM and large-angle convergent-beam electron diffraction. For the threading edge dislocations examined, the direction obtained by rotating the direction from the minimum of the dark contrast to the maximum of the bright contrast by 90° counterclockwise coincided with the Burgers-vector direction. Analysis based on the photoelastic effect further suggests that the phase contrast primarily reflects the sum of the two in-plane normal strain components, εxx + εyy, around the dislocation. These results demonstrate that phase-contrast microscopy can be used as a nondestructive optical method for determining the in-plane Burgers-vector direction of threading edge dislocations in GaN.
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BibTeX
@misc{ishikawa2026determination,
title = {{Determination of Burgers-vector directions of threading edge dislocations in GaN by phase-contrast microscopy}},
author = {Yukari Ishikawa and Maki Shimizu and Koji Sato and Kisara Matsumoto and Kazuki Ohnishi and Yongzhao Yao and Ryo Hattori},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.07837},
eprint = {2610.07837},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.07837},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Determination of Burgers-vector directions of threading edge dislocations in GaN by phase-contrast microscopy
AU - Yukari Ishikawa
AU - Maki Shimizu
AU - Koji Sato
AU - Kisara Matsumoto
AU - Kazuki Ohnishi
AU - Yongzhao Yao
AU - Ryo Hattori
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.07837
UR - https://arxiv.org/abs/2610.07837
AB - Phase-contrast microscopy enables rapid, nondestructive observation of threading dislocations in GaN, but the relationship between dislocation contrast and the Burgers vector has not been established. Here, we demonstrate that the in-plane Burgers-vector direction of threading edge dislocations in GaN can be determined from the arrangement of bright and dark contrast in phase-contrast microscopy images. The relationship was first established for threading edge dislocations in ammonothermal GaN whose Burgers vectors were independently determined by X-ray topography and was subsequently applied to hydride vapor phase epitaxy-grown GaN. The Burgers vector predicted from the phase contrast was verified by weak-beam dark-field TEM and large-angle convergent-beam electron diffraction. For the threading edge dislocations examined, the direction obtained by rotating the direction from the minimum of the dark contrast to the maximum of the bright contrast by 90° counterclockwise coincided with the Burgers-vector direction. Analysis based on the photoelastic effect further suggests that the phase contrast primarily reflects the sum of the two in-plane normal strain components, εxx + εyy, around the dislocation. These results demonstrate that phase-contrast microscopy can be used as a nondestructive optical method for determining the in-plane Burgers-vector direction of threading edge dislocations in GaN.
ER -