        A. Kranti, R. Yan, C.W. Lee, I. Ferain, R. Yu, N. Dehdashti Akhavan, P. Razavi, JP Colinge Tyndall National Institute, University College Cork, Cork, Ireland Email : jeanpierre.colinge@tyndall.ie                !"# $     %&   ’ ’ $      %(     %(  $   ’    (     ’  ()$ *    ’  ’% ’    %& $ I. INTRODUCTION The junctionless nanowire transistor (JNT) is a heavilydoped SOI nanowire resistor with an MOS gate that controls current flow. Doping concentration is constant and uniform throughout the device and typically ranges from 10 19 and 10 20 cm 3 . The device features bulk conduction instead of surface channel conduction. Junctionless fabrication process is greatly simplified, compared to standard CMOS since there are no doping concentration gradients in the device.[13] Figure 1: TEM cross section of a junctionless nanowire transistor. II. DEVICE PHYSICS The electrical characteristics of the JNT are remarkably identical to those of regular trigate MOSFETs. Figure 2 shows      characteristics. The device has an effective width of 25nm and   =1um. Extrapolating using   =1V,   =  0.3V and   =  +0.7V, L=20nm and a pitch of 50nm one finds that the device is capable of I OFF and I ON of 1nA/m and 1000A/m, respectively, without using any mobilityenhancing technique such as strain. Figure 2: Measured      characteristics of an nchannel device with W eff =25nm and L=1m. The physics of the JNT is quite different from that of standard multigate FETs. Depletion of the heavily doped nanowire creates a large electric field perpendicular to current flow below threshold, but above threshold the field drops to zero. This is the opposite of inversionmode (IM) or even accumulationmode (AM) devices where the field is highest when the device is turned on (Table I). The electron concentration profiles in cross sections of IM, AM and JNT devices are shown in Figures 3 and 4. Table I: Conduction mechanisms and E field perpendicular to current flow in inversionmode (IM), accumulation mode (AM) and junctionless (JNT) nanowire MuGFETs ( *%  #% IM Surface conduction High E field Surface conduction Low E field AM Surface conduction High E field Bulk conduction Low E field JNT Bulk conduction Low E field Bulk conduction High E field 978-1-4244-6661-0/10/$26.00 ©2010 IEEE 357