Groove-shaped defects in as-grown (001)-oriented β-Ga2O3 epilayers prepared by halide vapor phase epitaxy
Abstract
Groove-shaped defects (GSDs) degrade the surface flatness of as-grown (001)-oriented β-Ga2O3 epilayers and necessitate chemical mechanical polishing before device fabrication, increasing processing costs and the risk of damage. We investigated the morphology, subsurface structure, and formation mechanism of GSDs in a homoepitaxial layer grown by halide vapor phase epitaxy using synchrotron X-ray topography and electron microscopy. The GSDs extended several millimeters along [010] and consisted predominantly of (-102) basal facets bounded by steep (100) sidewalls. Their wafer-scale distribution showed a spatial correspondence with variations in wafer curvature, suggesting that local surface orientation influences GSD formation. Careful alignment of surface images with transmission X-ray topographs revealed no one-to-one correspondence between GSDs and substrate defects, providing no evidence that substrate dislocations serve as their nucleation sites. Instead, transmission electron microscopy revealed planar defects localized near the terminal boundaries where the faceted GSD sectors met the surrounding (001) growth region; no such defects were observed in specimens extracted from the middle of GSDs. These defects exhibited α-fringe contrast characteristic of inclined translational planar defects, with the dominant segments assigned to the (1-21) plane. The observations suggest that variations in local surface orientation and step supply may promote three-dimensional faceted growth, producing persistent (-102)/(100) sectors. The localized planar defects are therefore interpreted as consequences of growth-sector coalescence rather than the origins of GSD nucleation. These findings provide insight into the roles of wafer curvature and surface step supply in GSD formation.
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BibTeX
@misc{yao2026grooveshaped,
title = {{Groove-shaped defects in as-grown (001)-oriented $β$-Ga$_2$O$_3$ epilayers prepared by halide vapor phase epitaxy}},
author = {Yongzhao Yao and Daiki Katsube and Hirotaka Yamaguchi and Yukari Ishikawa},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.07209},
eprint = {2609.07209},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.07209},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Groove-shaped defects in as-grown (001)-oriented β-Ga_2O_3 epilayers prepared by halide vapor phase epitaxy
AU - Yongzhao Yao
AU - Daiki Katsube
AU - Hirotaka Yamaguchi
AU - Yukari Ishikawa
PY - 2026
DA - 2026/09/07
PB - arXiv
DO - 10.48550/arxiv.2609.07209
UR - https://arxiv.org/abs/2609.07209
AB - Groove-shaped defects (GSDs) degrade the surface flatness of as-grown (001)-oriented β-Ga_2O_3 epilayers and necessitate chemical mechanical polishing before device fabrication, increasing processing costs and the risk of damage. We investigated the morphology, subsurface structure, and formation mechanism of GSDs in a homoepitaxial layer grown by halide vapor phase epitaxy using synchrotron X-ray topography and electron microscopy. The GSDs extended several millimeters along [010] and consisted predominantly of (-102) basal facets bounded by steep (100) sidewalls. Their wafer-scale distribution showed a spatial correspondence with variations in wafer curvature, suggesting that local surface orientation influences GSD formation. Careful alignment of surface images with transmission X-ray topographs revealed no one-to-one correspondence between GSDs and substrate defects, providing no evidence that substrate dislocations serve as their nucleation sites. Instead, transmission electron microscopy revealed planar defects localized near the terminal boundaries where the faceted GSD sectors met the surrounding (001) growth region; no such defects were observed in specimens extracted from the middle of GSDs. These defects exhibited α-fringe contrast characteristic of inclined translational planar defects, with the dominant segments assigned to the (1-21) plane. The observations suggest that variations in local surface orientation and step supply may promote three-dimensional faceted growth, producing persistent (-102)/(100) sectors. The localized planar defects are therefore interpreted as consequences of growth-sector coalescence rather than the origins of GSD nucleation. These findings provide insight into the roles of wafer curvature and surface step supply in GSD formation.
ER -