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 $I_{\mathrm{ ds}}$ – $V_{\mathrm{ gs}}$ and $I_{\mathrm{ ds}}$ – $V_{\mathrm{ ds}}$ 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: $\propto V_{\mathrm{ gs}}^{2/3}$ for 1-D, $\propto V_{\mathrm{ gs}}$ for 2-D, and $\propto V_{\mathrm{ gs}}^{3/2}$ for 3-D, with profound implications on their delay performance versus power. In particular, for 1-D TFETs, $CV/I$ decreases with decreasing $V_{\mathrm{ dd}}$ , until reaching a minimum delay at $V_{\mathrm{ dd}} \approx 6kT/q$ , where the $kT$ width of the Fermi–Dirac distribution becomes the limiting factor.