Explaining the dependences of electron and hole mobilities in Si MOSFET´s inversion layer

In this paper we report a detailed study of the surface roughness (SR) limited mobility and, for the first time, a physical explanation of the different dependences of the electron and hole mobilities. Based on full-band Monte Carlo simulations, we show that the differences between hole and electron experimental mobilities can be accounted for by using a steeper tail of the SR power spectrum at high wave-vector values. The new power spectral density allows to fit all the experimental data at room and cryogenic temperature, with the same parameter values for both electrons and holes. The spatial dependence of the new SR spectrum is discussed and compared to the features of the SR described by exponential and Gaussian auto-covariance functions.