Experimental determination of electron and hole mobilities in MOS accumulation layers

This letter presents for the first time, the experimentally determined majority carder mobilities in the accumulation layer of a MOSFET for both p-type and n-type channel doping for a wide range of doping concentrations. The measured carrier mobility is observed to follow a universal behavior at high transverse fields, similar to that observed for minority carriers in MOS inversion layers, At the higher doping levels, the effective mobility for majority carriers at low to moderate transverse fields is found to be very close to the bulk mobility, This is believed to be due to carrier screening of the ionized impurity scattering which dominates at the higher doping concentrations.