The influence of point defects on the thermal conductivity of AlN crystals

The average bulk thermal conductivity of free-standing physical vapor transport and hydride vapor phase epitaxy single crystal AIN samples with different impurity concentrations is analyzed using the 3 omega method in the temperature range of 30-325 K. AIN wafers grown by physical vapor transport show significant variation in thermal conductivity at room temperature with values ranging between 268 W/m K and 339 W/m K. AIN crystals grown by hydride vapor phase epitaxy yield values between 298 W/m K and 341 W/m K at room temperature, suggesting that the same fundamental mechanisms limit the thermal conductivity of MN grown by both techniques. All samples in this work show phonon resonance behavior resulting from incorporated point defects. Samples shown by optical analysis to contain carbon-silicon complexes exhibit higher thermal conductivity above 100K. Phonon scattering by point defects is determined to be the main limiting factor for thermal conductivity of AIN within the investigated temperature range. Published by AIP Publishing.