{
  "abstract": "We present a systematic first-principles investigation of halide impurities (F and Cl) in Ga$_2$O$_3$ and Al$_2$O$_3$, considering both monoclinic and corundum phases. Our study of the structural properties, formation energies, and charge-state transition levels establishes the relative stability of different atomic configurations and charge states. We find that F and Cl on oxygen sites act as shallow donors in Ga$_2$O$_3$ in both the monoclinic and corundum phases. However, their behavior differs substantially as the band gap increases with greater Al compositions. Fluorine is prone to $DX$-center formation with increased Al composition, leading to self-compensation at 38% Al concentration in monoclinic (Al$_x$Ga$_{1-x}$)$_2$O$_3$ and 70% Al concentration in corundum (Al$_x$Ga$_{1-x}$)$_2$O$_3$. Chlorine is more resistant to $DX$-center formation: in monoclinic (Al$_x$Ga$_{1-x}$)$_2$O$_3$, Cl$_\\mathrm{O}$ on the lowest-energy oxygen site shows an onset of $DX$ behavior at 50% alloy composition, while in corundum (Al$_x$Ga$_{1-x}$)$_2$O$_3$ this onset for Cl$_\\mathrm{O}$ occurs only at Al concentrations as high as 84%. We also study F and Cl interstitials, finding that they act as compensating centers but also exhibit migration barriers that are low enough for them to be removed by post-growth annealing. Surprisingly, in both monoclinic and corundum Al$_2$O$_3$, Cl$_\\mathrm{O}$ exhibits a relatively shallow transition level located at $\\sim$0.48 eV below the conduction-band minimum, much shallower than F$_\\mathrm{O}$ and other donor candidates. These remarkable results identify Cl as an unusually promising donor candidate in (Al$_x$Ga$_{1-x}$)$_2$O$_3$ alloys and even pure Al$_2$O$_3$, although high formation energies and compensation will render observation of true $n$-type conductivity in Al$_2$O$_3$ difficult.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2608.30680",
  "author_total": 5,
  "authors": [
    {
      "name": "Sai Mu"
    },
    {
      "name": "Haochen Wang"
    },
    {
      "name": "Yongjoong Shin"
    },
    {
      "name": "Zhi-Hao Wang"
    },
    {
      "name": "Chris G. Van de Walle"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bvh7nz3a72gq2.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.30680",
  "fulltext_url": null,
  "id": "bvh7nz3a72gq2",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.30680",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "openalex",
      "2504|Ga2O3 and related materials"
    ]
  ],
  "openalex": "W7204922576",
  "pdf_url": "https://arxiv.org/pdf/2608.30680",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-31",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bvh7nz3a72gq2.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:41Z",
      "native_id": "2608.30680",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.30680"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Halide donors in monoclinic- and corundum-phase Ga$_2$O$_3$ and Al$_2$O$_3$",
  "title_text": "Halide donors in monoclinic- and corundum-phase Ga_2O_3 and Al_2O_3",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:41Z",
  "url": "https://research.draconitic.com/paper/bvh7nz3a72gq2",
  "venue": "arXiv",
  "versions": []
}