In-situ Patterned Damage-Free Etching of 3-Dimensional Structures in \b{eta}-Ga2O3 using Triethylgallium

TL;DR

This paper demonstrates anisotropic, damage-free etching of 3D structures in ta-Ga2O3 using triethylgallium in an MOCVD chamber, enabling high-quality fin fabrication with smooth sidewalls and preserved electrical properties.

Contribution

It introduces a novel in-situ TEGa etching method for ta-Ga2O3 that achieves anisotropic, damage-free patterning of complex 3D structures.

Findings

High anisotropy in etching due to crystal orientation

Smooth sidewalls achieved along specific crystal orientations

Schottky diodes show no change in donor concentration after etching

Abstract

In this work, we report on the anisotropic etching characteristics of \b{eta}-Ga2O3 using triethylgallium (TEGa) performed in-situ within an MOCVD chamber. At sufficiently high substrate temperature, TEGa can act as a strong etchant for \b{eta}-Ga2O3 utilizing the suboxide reaction between Ga and Ga2O3. We observe that due to monoclinic crystal structure of \b{eta}-Ga2O3, TEGa etching on both (010) and (001) substrates is highly anisotropic in nature, both in terms of sidewall roughness and lateral etch rate. Smooth sidewalls are only obtained along crystal orientations that minimize sidewall surface energy. Utilizing this technique we also demonstrate deep sub-micron fins with smooth sidewalls and high aspect ratios. Furthermore, we also demonstrate the damage free nature of TEGa etching by fabricating Schottky diodes on the etched surface which display no change in net donor concentration.