Ballistic thermal conductance limited by phonon roughness scattering: A comparison of power-law and Gaussian roughness

In this work, we have investigated the influence of power-law roughness on the ballistic thermal conductance K-TH for a nanosized beam adiabatically connected between two heat reservoirs. The sideways wall beam roughness is assumed to be power-law type, which is described by the roughness amplitude w, the in-plane roughness correlation length xi and the roughness exponent 0less than or equal toHless than or equal to1. Distinct differences occur in between power-law and Gaussian wall roughness. For power-law roughness with low roughness exponents H (0.5) the conductance drop is significantly smaller than that of Gaussian roughness assuming similar roughness ratios w/xi