Ab initio lattice thermal conductivity of bulk and thin-film $\alpha$-Al${}_2$O${}_3$

Abstract

The thermal conductivities ($\kappa$) of bulk and thin-film $\alpha$-Al${}_2$O${}_3$ are calculated from first principles using both the local density approximation (LDA), and the generalized gradient approximation (GGA) to exchange and correlation. The room temperature single crystal LDA value $\sim 39$W/m K agrees well with the experimental values $\sim 35-39$W/m K, whereas the GGA values are much smaller $\sim$26 W/m K. Throughout the temperature range, LDA is found to slightly overestimate $\kappa$ whereas GGA strongly underestimates it. We calculate the $\kappa$ of crystalline $\alpha$-Al${}_2$O${}_3$ thin films and observe a maximum of 79$\%$ reduction for $10$nm thickness.

arXiv comment10 pages, 4 figures, 1 table

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