Intrinsic thermal conductivity and its anisotropy of wurtzite InN

Despite wurtzite InN being a widely used semiconductor, its intrinsic thermal conductivity (κ) is still little known. In this work, the κ of wurtzite InN is studied from first principles. The calculated room temperature κ is 130 Wm−1K−1 and 145 Wm−1K−1 for the in-plane and out-of-plane direction, respectively, showing an anisotropy of about 11%. The anisotropy increases with decreasing temperature, and it reaches 20% at 100 K. The evident anisotropy is contrast to the conventionally used isotropic assumption, and is explained by performing comprehensive velocity analysis. We also calculate the cumulative κ as a function of mean free path, which can help understand the size dependence of κ in the non-bulk forms. The obtained cumulative κ is in good agreement with the experimental κ of InN films with thicknesses between 0.5 and 2.1 μm, and shows the size effect can persist up to 10 μm thickness at room temperature.