Scalable GaSb/InAs Tunnel FETs With Nonuniform Body Thickness.

GaSb/InAs heterojunction tunnel FETs are strong candidates in building future low-power ICs, as they could provide both steep subthreshold swing and large ON-state current ( I\mathrm{\scriptscriptstyle ON} ). However, at short-channel lengths, they suffer from large tunneling leakage originating from the small bandgap and small effective masses of the InAs channel. As proposed in this paper, this problem can be significantly mitigated by reducing the channel thickness, meanwhile retaining a thick source-channel tunnel junction, thus forming a design with a nonuniform body thickness. Because of the quantum confinement, the thin InAs channel offers a large bandgap and large effective masses, reducing the ambipolar and source-to-drain tunneling leakage at OFF-state. The thick GaSb/InAs tunnel junction, instead, offers a low tunnel barrier and small effective masses, allowing a large tunnel probability at ON-state. In addition, the confinement-induced band discontinuity enhances the tunnel electric field and creates a resonant state, further improving I\mathrm{\scriptscriptstyle ON} . Atomistic quantum transport simulations show that ballistic I\mathrm{\scriptscriptstyle ON}=284 A/m is obtained at 15-nm channel length, I\mathrm{\scriptscriptstyle OFF}=1\times 10^{-3} A/m, and V\mathrm{DD}=0.3 V, while with uniform body thickness, the largest achievable I\mathrm{\scriptscriptstyle ON} is only 25 A/m. Simulations also indicate that this design is scalable to sub-10-nm channel length. [ABSTRACT FROM AUTHOR]