RF Performance Projections of Negative-Capacitance FETs: fT, fmax, and gmfT/ID

As continuous development and optimization of negative-capacitance field-effect transistors (NCFETs) are pursued for digital applications, it is also desirable to examine the radio frequency (RF) performance of these devices, especially devices with the metal-ferroelectric- insulator-semiconductor (MFIS) structure. In this article, we use a combination of physics-based modeling and small-signal circuits to investigate the RF performance of MFIS NCFETs using three key device figures of merit: the well-known unity-current-gain (cutoff) frequency f
_T
and the well-known maximum oscillation frequency f
_max
, and another important metric specified by g
_m
f
_T
/I
_D
, where g
_m
is the transconductance and I
_D
is the dc drain current. We find that MFIS NCFETs achieve similar f
_T
and f
_max
performance to conventional MOSFETs, but offer a significant advantage in g
_m
f
_T
/I
_D
.