Physical understanding of low-field carrier mobility in silicon MOSFET inversion layer

Experimental and theoretical studies of the gate field dependencies of the low-field mobilities of electrons and holes show that by changing surface orientations and oxidation conditions the two-dimensional electron gas formulation can successfully explain η=1/3 (where η is the weighting factor of mobile charge density used in calculating the effective field for the universal mobility curve) for (111) electrons and holes: η=1/2 for (100) electrons. For the effective transverse field, E_eff, the mobility limited by the phonon scattering has E_eff^-3 dependences both for electrons and holes. It is also concluded that the surface mobility in the strong inversion regime is truly determined by the intrinsic properties of the silicon surface and follows Matthiessen´s rule as long as valley repopulation is taken into account