Channel electron mobility dependence on lateral electric field in field-effect transistors

A method is described to measure the channel charge density-mobility produc t in field-effect transistors as a function of lateral channel field. From knowledge of the channel charge density, the channel carrier mobility-later al field relation is determined. This method was applied to n-channel Si me tal-oxide-semiconductor field-effect transistors. The channel charge densit y was determined at low lateral field as a function of gate-to-channel volt age from capacitance measurements and this value was corrected to account f or electron saturation velocity effects at higher fields. The electron mobi lity-field results were obtained for lateral fields up to 2x10(5) V/cm, a f actor of 5-10 larger than previously obtained, and were fit to the conventi onal empirical relation for mobility, mu=mu(lf)[1+(mu(lf)xi(L)/v(sat))(beta )](-1/beta), where mu(lf) is mobility at small lateral fields, v(sat) is el ectron saturation velocity, xi(L) is the magnitude of the lateral channel f ield, and beta is an empirical fitting parameter; a best fit to this relati on was obtained for unity beta and v(sat) of 4x10(6) cm/s. (C) 2000 America n Institute of Physics. [S0021-8979(00)04502-3].