发表机构
Mie University; Japan Fine Ceramics Center（三重大学; 日本精细陶瓷中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过同步辐射X射线形貌和电子显微镜，揭示了卤化物气相外延生长的β-Ga2O3外延层中沟槽状缺陷的形貌、形成机制，发现其与晶圆曲率和表面台阶供给相关，而非衬底位错所致。
AI 中文摘要
沟槽状缺陷（GSDs）降低了（001）取向$\beta$-Ga$_2$O$_3$外延层原始表面的平整度，在器件制造前必须进行化学机械抛光，从而增加了加工成本和损伤风险。我们利用同步辐射X射线形貌术和电子显微镜，研究了通过卤化物气相外延生长的同质外延层中GSDs的形貌、亚表面结构和形成机制。GSDs沿[010]方向延伸数毫米，主要由（-102）底面小面组成，并以陡峭的（100）侧壁为边界。其晶圆尺度分布与晶圆曲率变化存在空间对应关系，表明局部表面取向影响GSDs的形成。将表面图像与透射X射线形貌图仔细对齐后发现，GSDs与衬底缺陷之间没有一一对应关系，没有证据表明衬底位错是其成核位点。相反，透射电子显微镜揭示了在小面化GSD扇区与周围（001）生长区域相接的末端边界附近存在局域平面缺陷；从GSD中部提取的样品中未观察到此类缺陷。这些缺陷表现出倾斜平移平面缺陷特征的$\alpha$-条纹衬度，主要段归属于（1-21）平面。观察结果表明，局部表面取向和台阶供给的变化可能促进三维小面化生长，产生持续的（-102）/（100）扇区。因此，局域平面缺陷被解释为生长扇区合并的结果，而非GSD成核的起源。这些发现为晶圆曲率和表面台阶供给在GSD形成中的作用提供了见解。
英文摘要
Groove-shaped defects (GSDs) degrade the surface flatness of as-grown (001)-oriented $β$-Ga$_2$O$_3$ 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.
Comments42 pages, 9 figures, 5 supplementary figures
