Phonon-defect scattering in high thermal conductivity diamond films

Abstract

We have investigated the thermal conductivity of large diamond samples grown by both hot filament and microwave plasma assisted chemical vapor deposition in order to study in detail the processes limiting heat conduction in this system. For samples containing nearly 100% diamond material and no apparent defects, the thermal conductivity is consistent with that expected for polycrystalline diamond with a given crystallite size. In films prepared by the hot filament technique, we observe an additional scattering of phonons near 60 K, which we attribute to either a resonant phonon-defect interaction, or a crossover from geometrical to Rayleigh phonon-defect scattering.