First-principles study of adatom interactions on the β-Ga₂O₃(010) surface

Monoclinic β-Ga₂O₃ is a wide-gap (~4.8 eV)¹ semiconductor with a high breakdown field. This renders Ga₂O₃ a promising candidate for high-power electronics and deep ultraviolet detectors. However, the growth rate and crystal quality of Ga₂O₃ thin films are limited by etching of the Ga₂O₃ surface due to suboxide (Ga₂O) formation. It has been reported that the growth rate of Ga₂O₃ in molecular beam epitaxy can be enhanced by an additional indium supply.² However, the mechanism by which In impacts growth remains elusive. To address this puzzle, we use density functional theory to explore the adsorption and diffusion of Ga and O adatoms on the Ga₂O₃(010) surface. The low-energy adsorption structures are studied for various Ga coverages. We illustrate the effect of the co-adsorption of In and Ga on the adsorption energetics and the diffusion barriers of O atoms. Our study holds clues to understanding the growth and etching mechanism of the Ga₂O₃ surface.

[1] T. Matsumoto, M. Aoki, A. Kinoshita, and T. Aono, Jpn. J. Appl. Phys. 13, 1578 (1974).
[2] P. Vogt, O. Brandt, H. Riechert, J. Lähnemann, and O. Bierwagen, Phys. Rev. Lett. 119, 196001 (2017).