A transistor with ON/OFF switching voltage much lower than the theoretical limit of conventional FETs is demonstrated. The basic concept is to use the gate-induced modulation of the longitudinal component of the electric field directly in the drain p-n(+) junction of a thin film SOI FET. This modulation enables the gate to remarkably control the avalanche-impact-ionization of electrons and holes in the junction. Experimental results and a theoretical model are presented. The strong dependence of avalanche-impact-ionization current on the electric field intensity results in an extremely low switching voltage (6 mV/decade at 300 K). (C) 2008 Elsevier Ltd. All rights reserved.