Temperature-dependent thermal conductivity in Mg-doped and undopedβ-Ga₂O₃bulk-crystals

Abstract

Abstract. For β-Ga 2 O 3 only little information exist concerning the thermal properties, especially the thermal conductivity λ. Here, the thermal conductivity is measured by applying the electrical 3ω-method on Czochralski-grown β-Ga 2 O 3 bulk crystals, which have a thickness of 200 µm and 800 µm. At room temperature the thermal conductivity along the [100]-direction in Mg-doped electrical insulating and undoped semiconducting β-Ga 2 O 3 is confirmed as 13 ± 1 Wm −1 K −1 for both crystals. The thermal conductivity increases for decreasing temperature down to 25 K to λ(25 K) = (5.3±0.6)·102 Wm −1 K −1 . The phonon contribution of λ dominates over the electron contribution below room temperature. The observed function λ(T ) is in accord with phonon-phonon-Umklapp scattering and the Debye-model for the specific heat at T 90 K which is about 0

Size effects in the thermal conductivity of gallium oxide (β-Ga2O3) films grown via open-atmosphere annealing of gallium nitride

“…This thermal conductivity is slightly lower than a previous measurement of the thermal conductivity of bulk, single crystalline b-Ga 2 O 3 ($13 W m À1 K À1 -black dotted line in Fig. 6), 49,50 and roughly half the value of the thermal conductivity of typical GaN HFET component AlGaN (16.6 W m À1 K À1 ). 51 Given the polycrystalline nature of our b-Ga 2 O 3 films, this reduction in thermal conductivity relative to the single crystalline value reported in Ref.…”

Three-dimensional anisotropic thermal conductivity tensor of single crystalline β-Ga2O3

“…9 Thermal conductivities of β-Ga2O3 along some highly symmetric directions have been reported previously by several authors. [10][11][12] For example, Guo et al 10 They observed a ~1/T dependence on the thermal conductivity for all the measured directions at temperatures >200 K and a 1/T 3 -1/T 4 dependence at temperatures <200 K. Handwerg et al 11 reported the thermal conductivity of Mg-doped and undoped β-Ga2O3 bulk crystals along the [100] direction from 4 to 300 K measured using the 3ω method. Galazka et al 12 also measured the thermal conductivity of β-Ga2O3 along the [010] direction using the laser flash method and reported a value of 21 W m -1 K -1 at room temperature.…”

“…directions from the current measurements over the temperature range from 80 to 400 K (solid symbols), with the literature measurements [10][11][12] (open symbols) included for comparison. It is interesting to note that although the current measurements agree well with the measurements by Guo et al 10 at high temperatures >200 K for both directions, the measurements by Guo et al 10 at low temperatures <200 K are significantly higher than the current measurements.…”

“…Temperature-dependent thermal conductivity of β-Ga2O3 along the [010] and [100] directions from the current measurements (red solid symbols) are compared with the literature measurement[10][11][12]28 (different open symbols). Calculations using the modified Callaway model with pure (dash-dot lines) and natural isotope (solid lines) and the first-principles predictions from the literature 29 (dashed lines) are also included for comparison.One possible reason could be that the samples might have different impurity concentrations, as impurity scattering usually dominantly affects the lattice thermal conductivity at low temperatures but not at high temperatures.…”

Temperature-dependent thermal conductivity and diffusivity of a Mg-doped insulatingβ-Ga2O3single crystal along [100], [010] and [001]

“…[10]). An exemplary measurement of ∆T (f ) ∝ U 2ω (f ) is shown in figure 4 together with a fit using equation 6 shown in figure 6.…”