Surface Electron Transport over a Helium Film

The mobility of surface electrons trapped over helium films covering solid substrates is calculated within the Boltzmann kinetic approach. It is shown that the electron mobility is dominated by the roughness scattering of the interface liquid helium-substrate. The mobility dependences on temperature and film thickness are determined and compared with available experimental data. The characteristic values for surface defect sizes of the substrate are in the mesoscopic scale.