On the effective mobility extraction by point-contact techniques on silicon-on-insulator substrates

In this work, we introduce the mobility vs. effective electric field representation for bare silicon-on-insulator substrates. The key factors determining the effective field in the silicon film are identified and modeled. This representation sheds light on the origins of the carrier mobility differences observed in passivated and non-passivated wafers. At low effective electric field, the roles of the Coulomb scattering, determined by the top-interface, and the impact of the silicon film thickness are clearly disclosed. Two and four point-contact characterization techniques are compared; caution is called when the two point Pseudo-MOSFET configuration is used without calibration of the current form factor, since it may lead to an underestimation of the mobility values. Nevertheless, when the effective field and current form factors are evaluated accurately, we report that the carrier mobility of the silicon film at high effective electric field, with passivated surface or not, obeys the Universal Mobility Curves.