A procedure for the determination of the effective mobility in an N-MOSFET in the moderate inversion region

We present a method for the determination of the electron mobility in the channel of a MOSFET in the moderate- and strong-inversion regions. The procedure is based on combining measured and computed current-voltage curves. Computed curves have been generated using a quantum-mechanical and a modified classical model. Results are shown to be in good agreement when the classical charge-sheet model was modified by including an inversion-layer depth, defined as the mean transverse position for the electrons in the channel. This method also allows for small geometry and series-resistance effects to be incorporated in a relatively simple way. Experimental mobility data were obtained in the 13-300 K temperature range for a wide range of transverse electric fields. The contribution of Coulomb scattering to the mobility has also been analysed experimentally by comparing the results to theoretical mobility curves calculated for the case of zero-charge centres.