Explaining the dependences of the hole and electron mobilities in Si inversion layers

In this work the hole surface roughness-limited mobility in Si MOSFETs is investigated. Based on full-band Monte Carlo simulations and on an equivalent relaxation-time numerical model, we show that the differences between hole and electron experimental mobilities are not due to any peculiar physics of the valence band. They can be instead accounted for by a suitable shape of the power spectrum describing the surface roughness. The new power spectrum explains the experimental dependences of both electron and hole mobilities using the same surface roughness parameters. Finally the spatial features of the roughness described by the new spectrum are discussed and compared to those represented by Gaussian and exponential auto-covariance functions.