Quasi-ballistic thermal transport in Al0.1Ga0.9N thin film semiconductors
Résumé
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 Lévy analysis of the quasi-ballistic heat conduction reveals superdiffusion exponents a=1.70+-0.06 at room temperature and a=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.