Effect of shifted gate stack engineering over negative capacitance tunnel field effect transistor (NCTFET)

Abstract

In this work, the performance of negative capacitance field effect transistor is closely investigated with different source material to improvise the transfer characteristics and sub-threshold swing. Tunnel Field Effect Transistor (TFET) being a strong competitor of conventional MOSFET for low power applications has its abilities to pull down Subthreshold Swing (SS) below fundamental limit but it has its own limitations of lower ION current and existence of ambipolar region for lower VGS voltage range. This ambipolar behavior is strongly seen in case of silicon source NCTFET but when source material is replaced with Germanium, a heterojunction is formed at source channel junction, and because of that, improvised result is obtained in terms of steeper subthreshold slope and ION/IOFF ratio. This work compares the transfer characteristics obtained in case of Si-Source and Ge-Source Negative Capacitance Tunnel Field Effect Transistor (NCTFET). The results obtained indicates that heterojunction NCTFET gives a subthreshold swing of 56.6 mV dec−1 and enhances ION/IOFF ratio to 0.24 × 108 in magnitude.