The phonon drag and diffusion thermopower of Si inversion layers

Abstract
New accurate results for the thermopower of Si inversion layers are compared with the calculated screened phonon-drag thermopower. Good agreement is obtained for both the temperature dependence and the magnitude, except at the lowest temperatures, when a change of sign to positive thermopower is observed. This the authors interpret as being due to the diffusion thermopower associated with surface roughness scattering.