Dimensionality Dependence of TFET Performance Down to 0.1 V Supply Voltage

With the recent emergence of 1-D and 2-D semiconductors, this brief assesses the performance of tunnel FETs (TFETs) made in semiconductors of different dimensionalities. The major difference among them arises from the density-of-states associated with the momentum in the direction perpendicular to the tunneling path. By applying an analytic model with an exponential barrier, continuous I
_ds
-V
_gs
and I
_ds
-V
_ds
characteristics are generated for any dimensionality and heterojunction bandgap. In the limit of zero-staggered bandgap, the maximum TFET currents exhibit different dependences on gate voltage: ∝V
_gs
^2/3
for 1-D, ∝V
_gs
for 2-D, and ∝V
_gs
^3/2
for 3-D, with profound implications on their delay performance versus power. In particular, for 1-D TFETs, CV/I decreases with decreasing V
_dd
, until reaching a minimum delay at V
_dd
≈ 6kT/q, where the kT width of the Fermi-Dirac distribution becomes the limiting factor.