{
  "abstract": "We report the properties of hexagonal (space group P6/mmm) scandium diboride ($\\mathrm{ScB}_2$) single crystals grown by a laser diode floating zone method at growth rates of ~1mm/hr under B-rich conditions with (002) rocking curve widths $Δω$=38'' approaching the quality of commercial SiC/GaN substrates. Lattice expansion measurements reveal matching to $\\mathrm{Al_{0.55}Ga_{0.45}N}$ with a coefficient of thermal expansion ~5ppm/K at typical AlGaN growth temperatures, enabling thick AlGaN layers for ultra-wide bandgap (UWBG) power electronics >1kV. We measure semi-metallic room temperature resistivity ~15$μΩ$ cm, climbing to ~93$μΩ$ cm at 773K with a $T^2$ dependence effectively eliminating substrate parasitic resistance, the limiting factor in exploiting the full potential of UWBG. The Debye temperature $θ_{D,ScB_2}$ from heat capacity and lattice expansion is ~850K well matched to $θ_{D,ScB_2}$, but lower than the 1100K measured for Sc-rich growth conditions. We discuss Debye matching as a key substrate codesign criterion providing significant overlap in phonon modes for heat removal and thermal matching during AlGaN growth. The competitive thermal conductivity at room temperature 53W/mK is half that from full first principles calculations, a discrepancy we attribute to the presence of Sc-vacancies generated by B-rich growth. while the resistivity is ~2x the theoretical value, indicating that both electrons and phonons play equal role in thermal transport. The smooth ~2.5nm rms roughness surface enables advanced heat removal modalities through engineered phonon bridges and phonon polaritons in $\\mathrm{ScB}_2$/AlGaN interfacial heterostructures, potentially allowing ~10-100x increase in power handling over state-of-the-art GaN/SiC.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.24856",
  "author_total": 25,
  "authors": [
    {
      "name": "MVS Chandrashekhar"
    },
    {
      "name": "Daniel Joel Harrison"
    },
    {
      "name": "Ahamed Raihan"
    },
    {
      "name": "Astrid D. Kengne"
    },
    {
      "name": "R. Shipra"
    },
    {
      "name": "Han Xie"
    },
    {
      "name": "Tasnia Jabin"
    },
    {
      "name": "Monte Hendrix"
    },
    {
      "name": "Ethan Scott"
    },
    {
      "name": "Roshan S. Annam"
    },
    {
      "name": "Sharad Mahatara"
    },
    {
      "name": "Evan N. Crites"
    },
    {
      "name": "Allana G. Iwanicki"
    },
    {
      "name": "Luke J. Meiler"
    },
    {
      "name": "Maxime Siegler"
    },
    {
      "name": "Renae N. Gannon"
    },
    {
      "name": "Steven R Spurgeon"
    },
    {
      "name": "Ashutosh Giri"
    },
    {
      "name": "Rajeswari Kolagani"
    },
    {
      "name": "Joshua A. Burrow"
    },
    {
      "name": "Stephan Lany"
    },
    {
      "name": "Patrick Hopkins"
    },
    {
      "name": "Tyrel M. McQueen"
    },
    {
      "name": "Michael Spencer"
    },
    {
      "name": "Satya Khushwaha"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/czqev4e3q7hek.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.24856",
  "fulltext_url": null,
  "id": "czqev4e3q7hek",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.24856",
  "language": null,
  "licence": "CC-BY-NC-ND-4.0",
  "licence_label": "CC BY-NC-ND 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by-nc-nd/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "openalex",
      "3104|GaN-based semiconductor devices and materials"
    ]
  ],
  "openalex": "W7214037314",
  "pdf_url": "https://arxiv.org/pdf/2609.24856",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/czqev4e3q7hek.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:19Z",
      "native_id": "2609.24856",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.24856"
    }
  ],
  "subjects": [
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Scandium diboride: a semi-metallic, lattice, thermally matched substrate for vertical AlGaN power electronics",
  "title_text": "Scandium diboride: a semi-metallic, lattice, thermally matched substrate for vertical AlGaN power electronics",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:19Z",
  "url": "https://research.draconitic.com/paper/czqev4e3q7hek",
  "venue": "arXiv",
  "versions": []
}