Analytical modeling of current-voltage characteristics of ferroelectric tunneling field effect transistor

Abstract

In this work a modified structure of Tunneling Field Effect Transistor (TFET) has been proposed incorporating Ferroelectric oxide as the gate oxide, called the Ferroelectric Tunneling FET (Fe-TFET). The TFET device is one of the novel devices for a low-power digital application due to their band to band tunneling mechanism and it exhibits a very small leakage current, high drive current and lower subthreshold slope. Fe-FET is also introduced by integrating ferroelectric material operating in the negative capacitance region that acts as a step-up transformer of the surface potential in a traditional MOSFET structure to achieve a steeper subthreshold slope. The proposed device (Fe-TFET) effectively combines the mechanism of TFET and the theoretical concept of Fe-FET. A simple tentative analytical ON current model of the proposed device is also presented here. By using the double gate configuration of this newly modified device named Fe-TFET, it is feasible to achieve much lower SS and can get sufficiently high drive current at a very low operating voltage. Fe-TFET gives ON current as high as 0.02 A/μm for a gate voltage of 0.4V, according to the results yielded from the analytical model. Thus the ION/IOFF ratio becomes ~ 108 which is greater than that of a MOSFET and also for traditional TFET. OFF current exponentially increases with the threshold voltage reduction. So, in order to limit OFF current while maintaining a satisfactory ON current the subthreshold slope has to go down. This work provides physics based reasoning behind the multiplicative improvement in the subthreshold slope for the proposed device which gives ~40mV/dec subthreshold slope. Finally it demonstrates that the device performance can be amended in accordance with the technology of different band gap materials like Si, GaAs, Ge and InAs and different Ferroelectric oxides like BaTiO3 and SrTiO3.