In situ etching using Ga flux in an ultra-high vacuum environment like molecular beam epitaxy is introduced as a method to make high aspect ratio three-dimensional (3D) structures in $\beta$-Ga₂O₃. Etching of $\beta$-Ga₂O₃ due to excess Ga adatoms on the epilayer surface had been viewed as non-ideal for epitaxial growth especially since it results in plateauing and lowering of the growth rate. In this study, we use this well-known reaction from epitaxial growth to intentionally etch $\beta$-Ga₂O₃. We demonstrate etch rate ranging from 2.9 to 30 nm/min with the highest reported etch rate being only limited by the highest Ga flux used. Patterned in situ etching is also demonstrated and used to study the effect of fin orientation on the sidewall profiles and dopant (Si) segregation on the etched surface. Using in situ Ga etching, we also demonstrate 150 nm wide fins and 200 nm wide nanopillars with high aspect ratio. This etching method could enable future development of highly scaled vertical and lateral 3D devices in $\beta$-Ga₂O₃.

中文翻译：

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使用原子镓通量对β-Ga2O3进行平面和三维无损伤蚀刻

介绍了在分子束外延等超高真空环境中使用 Ga 通量的原位蚀刻作为一种制造高深宽比三维 (3D) 结构的方法。$\beta$-Ga ₂ O ₃。蚀刻$\beta$-Ga ₂ O ₃由于外延层表面上的过量 Ga 吸附原子而被视为非外延生长的理想选择，特别是因为它导致稳定和生长速率的降低。在这项研究中，我们使用了这种众所周知的外延生长反应来有意蚀刻$\beta$-Ga ₂ O ₃。我们展示了 2.9 到 30 nm/min 的蚀刻速率，最高报告的蚀刻速率仅受所使用的最高 Ga 通量的限制。还演示了原位蚀刻图案化，并用于研究鳍片取向对侧壁轮廓和蚀刻表面上的掺杂剂 (Si) 偏析的影响。使用原位Ga 蚀刻，我们还展示了 150 nm 宽的鳍和 200 nm 宽的具有高纵横比的纳米柱。这种蚀刻方法可以使未来开发高度缩放的垂直和横向 3D 设备成为可能。$\beta$-Ga ₂ O ₃。