A Review on Role of Epitaxial Engineering in Improving the Drive Current and Subthreshold Swing in Area Scaled Tunnel FETs

In this work, to support the need of ultra-low power applications with "Always-ON" feature, a review of area-scaled tunneling is carried out in different Field Effect Transistor (FET) architectures. Area-scaled tunnel FETs (TFETs) provides the solution to low drive current and degraded Subthreshold Swing (SS) in tunnel FETs by significantly increasing the area of cross-section available for Band-to-Band Tunneling (BTBT) by depositing an epitaxial layer above the source region. We have investigated the role of epitaxial engineering in ultra scaled architectures like FinFET and Gate-All-Around (GAA) FET. Gate over source overlap length (L
GS,ov
), epitaxial-layer thickness (T
EPI
) and epitaxial-layer doping (N
EPI
) are considered as the key parameters of epitaxial based TFETs. It has been investigated that the performance parameters like ON-current (I
on
), OFF-current (I
off
), I
on
/I
off
and SS are significantly affected by employing the epi-layer. Optimum value of these key parameters should be carefully chosen to outperform when compared with their counterparts.