Contribution of the decay of optical phonons into acoustic phonons to the thermal conductivity of AlN

The thermal conductivity along two high-symmetry directions of several aluminum nitride (AlN) single crystals differing in their mass-fluctuation phonon-scattering parameter is described accurately in the full temperature range by taking into account the contribution of optical phonon decay into acoustic phonon. The accuracy of the proposed model shows the fundamental role of the optical phonon in the thermal conductivity of semiconductor materials.

Figure 1

(Color online) AlN thermal conductivity $k\left(T\right)$ along the $\Gamma A$ and $\Gamma K$ crystal directions. Symbols: measured data. Dashed lines: modeling by using Eq. (1) and values of $\Gamma$ obtained from the least squares method. Dotted lines: attempt to account for more experimental points by decreasing $\Gamma$. Solid lines: modeling by using the model proposed in this work

Figure 2

(Color online) Ge thermal conductivity. Symbols: experimental data obtained from Refs. 5, 6. Dashed lines: Fitting to the experimental data by using the MCT. Solid lines: Fitting to the experimental data using the proposed model.

Figure 3

(Color online) (a) Symbols: Experimental $k\left(T\right)$ data reported by Slack et al. (Ref. 24). Dashed line: fitting to the experimental data using Eq. (1). Solid line: fitting to the experimental data by using the proposed model. Dot-dashed line: estimation of $k\left(T\right)$ for pure AlN by using the model in Ref. 24. Dotted line: estimation of $k\left(T\right)$ for pure AlN by using the proposed model. (b) $k$ at RT for pure AlN, predicted from this work and Ref. 24, compared to a plot of $k$ for several adamantine structure crystals vs the LS parameter.