Electron-hole bilayer tunnel FET for steep subthreshold swing and improved ON current

Abstract

We propose a novel Tunnel field-effect transistor (TFET) concept called the electron-hole bilayer TFET (EHBTFET). This device exploits the carrier tunneling through a bias-induced electron-hole bilayer in order to achieve improved switching and higher drive currents when compared to a lateral p-i-n junction TFET. The device principle and performances are studied by 2D numerical simulations. Output and transfer characteristics, as well as the impact of back gate bias, silicon thickness and gate length on the device behavior are evaluated. Near ideal average subthreshold slope (SS <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AVG</sub> ~ 12 mV/dec over 6 decades of current) and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> /I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</sub> >; 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</sub> = V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> = 0.5 V figures of merit are obtained, due to the OFF-ON binary transition which leads to the abrupt onset of the band-to-band tunneling inside the silicon channel. Drive current (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</sub> ) in the EHBTFET is 3× higher that in traditional all-Si Tunnel FET but below 0.1 μA/μm.