Gate Metal Work Function Engineering for the Improvement of Electrostatic Behaviour of Doped Tunnel Field Effect Transistor

Abstract

This paper reports a new configuration of tunnel field-effect transistor (TFET) for improving the current drivability of device, reduced threshold voltage, suppress ambipolar behaviour and better high-frequency response of the device. For this, a P+-I-N+ type structure has been considered, and then gate electrode is divided into three parts which is placed over the channel region. Low work function metal is applied at the source/channel junction side to increase the steepness in the band at source/channel interface, which increases electron tunnelling rate, that results in higher ON-state current and reduction in threshold voltage. At the same time, low work function metal electrode is applied at the drain/channel junction side, which is helpful for the suppression of ambipolar behaviour of the device. The simulated results show excellent improvement in ON-state current, lowering of the threshold voltage, suppression in ambipolar behaviour and drastic improvement in analog/RF parameters of the device. To show the impact of proposed modification and to analyse the device behaviour, parameters such as transfer characteristics and energy band diagram are considered as DC figure of merits, whereas transconductance (gm), output onductance (gds), gate-to-draincapacitance (Cgd)), cut off frequency (fT) and gain bandwidth product (GBP) are used as RF performance parameters. All the simulations have been performed by Silvaco ATLAS simulator.