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β-Ga2O3(001) surface reconstructions from first principles and experiment

Konstantin Lion1,2,*,†, Piero Mazzolini3,‡, Kingsley Egbo3, Toni Markurt4, Oliver Bierwagen3, Martin Albrecht4, and Claudia Draxl1

  • *Contact author: lion@ms1p.org
  • †Present address: Molecular Simulations from First Principles e.V., Berlin, Germany.
  • ‡Present address: Department of Mathematical Physical and Computer Sciences, University of Parma, Parma, Italy.
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Phys. Rev. Materials 10, 043603 – Published 30 April, 2026

DOI: https://doi.org/10.1103/wzfr-rllh

Abstract

We present a comprehensive investigation of reconstructions on β-Ga2O3(001) combining first-principles calculations with experimental observations. Using ab initio atomistic thermodynamics and replica-exchange grand-canonical molecular dynamics simulations, we explore the configurational space of possible reconstructions under varying chemical potentials of oxygen and gallium. Our calculations reveal several stable surface reconstructions, most notably a previously unreported 1×2 reconstruction consisting of paired GaO4 tetrahedra that exhibits remarkable stability across a wide range of experimental growth conditions. In this reconstruction, two Ga atoms share one oxygen bond and are separated by a distance of 2.64Å along the [010] direction. High-angle annular dark-field scanning transmission electron microscopy imaging of homoepitaxially grown (001) layers is consistent with the predicted structure. Additional investigations of possible indium substitution at the surface sites, which can occur during indium-mediated metal-exchange catalysis via molecular beam epitaxial growth, reveal a cooperative effect in In incorporation, with distinct stability regions for In-substituted structures under O-rich conditions. Our findings provide an understanding for controlling surface properties during epitaxial growth of β-Ga2O3(001).

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Phys. Rev. Materials 10, 043603– Published 30 April, 2026
  • Received 10 October 2025
  • Accepted 17 February 2026
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