Significance of Work Function Fluctuations in SiGe/Si Hetero-Nanosheet Tunnel-FET at Sub-3 nm Nodes

This work highlights the work-function-fluctuation (WKF) of the strained Si
_0.6
Ge
_0.4
p-n-p-n tunneling field-effect transistor (TFET) using nanosheet geometry at sub-3 nm technology nodes. The reported work exploits 3000 samples to signify the key results of several dc factors such as ON- and OFF-state currents (
${I}_{ \mathrm{\scriptscriptstyle ON}}$
and
${I}_{ \mathrm{\scriptscriptstyle OFF}}$
), threshold voltage (
${V}_{\text {th}}$
), and the subthreshold swing (SS). Fewer WKFs are identified for higher metal grain number (MGN) due to the shaped low grain size. Collective average energy reduction of 10–15 meV as low with high MGN and 40–60 meV as high with low MGN for a group of metal-grains closer to the tunneling junction is observed. This huge impact of energy reduction proportionally affects electron transport due to reduction in tunneling length. High variability in
${V}_{\text {th}}$
(
$\geq {15}$
%) is identified at progressively diminished MGN due to parabolic behavior of variation. Furthermore, marginal variation in SS,
${I}_{ \mathrm{\scriptscriptstyle ON}}$
, and
${I}_{ \mathrm{\scriptscriptstyle OFF}}$
are observed because of the WKF dependability over the subthreshold region of operation.