Temperature-dependent thermal conductivity and diffusivity of a Mg-doped insulating $\beta$-$\mathrm{G}{\mathrm{a}}_2{\mathrm{O}}_3$ single crystal along [100], [010] and [001]

Abstract

The monoclinic crystal structure of $\beta$-$\mathrm{G}{\mathrm{a}}_2{\mathrm{O}}_3$ leads to significant anisotropy of the thermal properties. The 2$\omega$-method is used to measure the thermal diffusivity $D$ in [010] and [001] direction respectively and to determine the thermal conductivity values $\lambda$ of the [100], [010] and [001] direction from the same insulating Mg doped $\beta$-$\mathrm{G}{\mathrm{a}}_2{\mathrm{O}}_3$ single crystal. We detect a temperature independent anisotropy factor of both the thermal diffusivity and conductivity values of $D_{[010]}/D_{[001]}={\lambda }_{[010]}/{\lambda }_{[001]}=1.4\pm 0.1$. The temperature-dependence is in accord with phonon-phonon-Umklapp scattering processes from 300 K down to 150 K. Below 150 K point-defect-scattering lowers the estimated phonon-phonon-Umklapp-scattering values.

11 pages, 8 figures

References in corpus (2)

• Anisotropic Thermal Conductivity in Single Crystal beta-Gallium Oxide
• Temperature-dependent thermal conductivity in Mg-doped and undoped $\beta$-$\mathrm{G}{\mathrm{a}}_2{\mathrm{O}}_3$ bulk-crystals

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• Resistive and ballistic phonon transport in $\beta$-Ga${}_2$O${}_3$