Experimental demonstration of strained Si nanowire GAA n-TFETs and inverter operation with complementary TFET logic at low supply voltages

Abstract

In this work, strained Si (sSi) nanowire array of n-TFETs with gates all around (GAA) yielding ON-currents of 5μA/μm at a supply voltage Vdd=0.5V are presented. Tilted ion implantation with BF2+ into NiSi2 dopant has been used to form a highly doped pocket for the source to channel tunneling junction. These devices indicate sub-threshold slopes (SS) below 60mV/dec for Id<10−4μA/μm at Vds=0.1V at room temperature. Common analog device characteristics have been determined at Vdd=0.5V resulting in a transconductance gm=24μS/μm, transconductance efficiency gm/Id=23V−1 and the conductance gd=0.8μS/μm normalized to the gate width. Based on the good saturation behavior in the output characteristic, an intrinsic gain of 188 is observed. In addition, we present operation of the first experimental sSi GAA NW C-TFET inverter. In spite of ambipolar behavior, the voltage transfer curves (VTC) indicate wide and constant noise margin levels with steep transitions offering a voltage gain of 25 at Vdd=1V.