Influence of surface modification on the quality factor of microresonators

Noise measurements were performed to determine the quality factor (Q) as a function of gas pressure P for microresonators in cantilever form with systematically modified surfaces. In the free-molecular regime, which is dominated by internal energy losses, Q was substantially decreased by more than an order of magnitude with increasing surface roughness. At higher pressures, within the molecular regime, Q showed the typical inverse linear dependence on pressure Q~P^-1. However, in the molecular regime the Q factor also showed a strong dependence on surface morphology as indicated by surface area calculations using measured roughness data and compared to those obtained from Q~P^-1 plots.