Quasi-Ballistic Thermal Transport In Al0.1ga0.9n Thin Film Semiconductors

We investigate thermal transport in high-quality Al0.1Ga0.9N thin films grown using plasma-assisted molecular beam epitaxy by time-domain thermoreflectance (TDTR) in the 100 K-500K temperature range. The apparent thermal conductivity at 300K and 500K drops by 30% when the laser modulation frequency is increased from 0.8MHz to 10MHz. Tempered Levy analysis of the quasi-ballistic heat conduction reveals superdiffusion exponents alpha approximate to 1.70 +/- 0.06 at room temperature and alpha approximate to 1.83 +/- 0.16 at 500 K. We describe limitations in concurrent extraction of other model parameters and also discuss the impact of boundary scattering in the 100 K-200K temperature range. Published by AIP Publishing.