Planar and three-dimensional damage-free etching of β-Ga2O3 using atomic gallium flux

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.

Automated summary

In this study, in situ etching using Ga flux is introduced as a method to create high aspect ratio three-dimensional structures in beta-Ga2O3 in an ultra-high vacuum environment. The etching rate ranges from 2.9 to 30 nm/min, and patterned in situ etching is also demonstrated to study the effects of fin orientation and dopant segregation on the etched surface. This method could enable the development of highly scaled vertical and lateral 3D devices in beta-Ga2O3.