Mound surface roughness effects on the thermal capacitance of thin films

We investigate the influence of roughness at a nanometer scale on the thermal properties of thin films. It is shown that the roughness causes an increase of the thermal capacitance. For mound rough surfaces the increase of the thermal capacitance depends strongly on the relative magnitude of the average mound separation λ and the system correlation length ζ. Indeed, a rather complex behavior develops for ζ>λ, while for ζ<λ a smooth decrease of the capacitance as a function of the average mound separation λ takes place. Finally, the roughness strongly affects the thermal capacitance as a function of the film thickness as long as ζ