Enhanced thermal conductivity of (010) (AlxGa1-x)2O3 epitaxial films utilizing indium-catalyzed molecular beam epitaxy
Abstract
(AlxGa1-x)2O3/beta-Ga2O3 transistors are an emerging candidate for high-power and high-frequency electronic devices. beta-Ga2O3 in particular is notably limited for anisotropic low thermal conductivity, which is further reduced in (AlxGa1-x)2O3 due to alloy and other defect-driven phonon scattering mechanisms. In this work we show that the thermal conductivity of (010) oriented (AlxGa1-x)2O3 thin films for 0.01 < x < 0.20, measured using time-domain thermoreflectance (TDTR), is limited by alloy scattering without observable adverse scattering by additional defects. This is enabled through the synthesis of the (AlxGa1-x)2O3 films using molecular beam epitaxy (MBE) on \b{eta}-Ga2O3 substrates, leveraging indium-catalyzed growth to suppress dislocation formation and phase separation to achieve single-phase pseudomorphic films up to x = 0.2. This growth process improved the thermal conductivity of (AlxGa1-x)2O3 by 2X as compared to previously reported values. For increasing Al composition (x), we observe a steady decline in (AlxGa1-x)2O3 thermal conductivity due to alloy scattering which is validated using virtual crystal approximation (VCA) model. We also show that the thermal boundary conductance across the Al/(AlxGa1-x)2O3 interface is reduced with increasing x, which we posit is due to the stiffening of the (AlxGa1-x)2O3 acoustic modes with increasing x by comparing experimental results with a diffuse mismatch model (DMM). Overall, these thermal characteristics provide valuable insights for designing heterostructures with optimized interfaces and composition.
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BibTeX
@misc{gowda2026enhanced,
title = {{Enhanced thermal conductivity of (010) (AlxGa1-x)2O3 epitaxial films utilizing indium-catalyzed molecular beam epitaxy}},
author = {Shivashree Gowda and Stephen Schaefer and Ethan A. Scott and Samreen Khan and Patrick E. Hopkins and M. Brooks Tellekamp},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.24081},
eprint = {2609.24081},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.24081},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Enhanced thermal conductivity of (010) (AlxGa1-x)2O3 epitaxial films utilizing indium-catalyzed molecular beam epitaxy
AU - Shivashree Gowda
AU - Stephen Schaefer
AU - Ethan A. Scott
AU - Samreen Khan
AU - Patrick E. Hopkins
AU - M. Brooks Tellekamp
PY - 2026
DA - 2026/09/21
PB - arXiv
DO - 10.48550/arxiv.2609.24081
UR - https://arxiv.org/abs/2609.24081
AB - (AlxGa1-x)2O3/beta-Ga2O3 transistors are an emerging candidate for high-power and high-frequency electronic devices. beta-Ga2O3 in particular is notably limited for anisotropic low thermal conductivity, which is further reduced in (AlxGa1-x)2O3 due to alloy and other defect-driven phonon scattering mechanisms. In this work we show that the thermal conductivity of (010) oriented (AlxGa1-x)2O3 thin films for 0.01 < x < 0.20, measured using time-domain thermoreflectance (TDTR), is limited by alloy scattering without observable adverse scattering by additional defects. This is enabled through the synthesis of the (AlxGa1-x)2O3 films using molecular beam epitaxy (MBE) on \b{eta}-Ga2O3 substrates, leveraging indium-catalyzed growth to suppress dislocation formation and phase separation to achieve single-phase pseudomorphic films up to x = 0.2. This growth process improved the thermal conductivity of (AlxGa1-x)2O3 by 2X as compared to previously reported values. For increasing Al composition (x), we observe a steady decline in (AlxGa1-x)2O3 thermal conductivity due to alloy scattering which is validated using virtual crystal approximation (VCA) model. We also show that the thermal boundary conductance across the Al/(AlxGa1-x)2O3 interface is reduced with increasing x, which we posit is due to the stiffening of the (AlxGa1-x)2O3 acoustic modes with increasing x by comparing experimental results with a diffuse mismatch model (DMM). Overall, these thermal characteristics provide valuable insights for designing heterostructures with optimized interfaces and composition.
ER -