Work Function Engineering for Performance Improvement in Leaky Negative Capacitance FETs

We analyze the effects of ferroelectric leakage on the performance of a negative capacitance field-effect transistor (NCFET), which has an intermediate metallic layer between the ferroelectric and the high-K dielectric. We show that, when designed without taking the dielectric leakage into account, the NCFET performance can actually degrade significantlywith respect to that of the baseline FET. To overcome these detrimental effects of leakage, we propose the concept of work-function engineering, where metals of dissimilar work-functions are used for the external gate electrode and the intermediate metallic layer. Using this approach, the ferroelectric charge-voltage characteristic is shifted along the voltage axis, which results in superior performance of the NCFET.