New method for assessment of depletion charge dependence of mobility in short-channel silicon MOS transistors

An original method for the extraction of the depletion charge mobility dependency coefficient alpha based on the exploitation of the body-to-gate transconductance ratio g_b/g_m(V_g) MOSFET characteristics is presented. This method allows the demonstration of the fact that alpha is a parameter strongly dependent on channel length for both device types (p or n). Moreover, it is shown that the channel length reduction of alpha is closely correlated to that of the depletion charge to the gate oxide capacitance ratio C_d/C_ox due to the increase of charge sharing effect when scaling down the devices.