Negative Capacitors and Applications

The long-standing tug-of-war between off-state leakage
power consumption and switching speed has posed severe
challenges to the scaling of semiconductor devices.
Deeply scaled short-channel transistors are faster but consume
more off-state power. This power vs speed trade-off
stems from the fundamental physical limit related to the
thermionic emission that governs switching in field-effect
transistors. There is a broad consensus in the semiconductor
industry that future progress is impossible unless the
next-generation transistors and circuits overcome the so-called
Boltzmann limit associated with thermionic emission
over a barrier and offer a steeper on-off switching to
enable a more aggressive voltage scaling.
In this chapter, we explain the need for and suggest an
intuitive classification of the emerging transistor technologies.
We use two illustrative examples of next-generation
transistors (i.e., negative capacitance FET (NCFET) and
phase FET (PhaseFET)) to explain the relative merits of
gate-controlled vs channel-controlled steep-slope switching.
We explain the basic principle of device operation,
summarize the experimental results reported in the literature,
and highlight the speed and reliability challenges to
be resolved before the devices are integrated into practical
systems. In addition, the chapter includes a careful analysis
of circuits based on these emerging transistor technologies
with applications toward Boolean logic, memories,
and non-Boolean computing. The analysis suggests
relative merits of various circuit designs and applications pecific
opportunities for significant power-performance
improvement.