FIG. 1 : (a) View of the transverse section in the middle of the devices with abrupt constrictions. Square source and drain (red) are 4 nm long uniformly doped at ND=1020 cm3. Each AR (yellow) contains one impurity at its center (red circle). The widths of AR for the three considered devices are WAR=3.6 nm, 2.8 nm, and 2.4 nm. Blue regions are 2 nm long spacer of intrinsic silicon to minimize the influence of the gate on the AR. (b) Corresponding ID–VGS characteristics in both logarithmic and linear scales .
This work theoretically studies the influence of both the geometry and the discrete nature of dopants of the access regions in ultra-scaled nanowire transistors. By means of self-consistent quantum transport simulations, we show that discrete dopants induce quasi-localized states which govern carrier injection into the channel. Carrier injection can be enhanced by taking advantage of the dielectric confinement occurring in these access regions. We demonstrate that the optimization of access resistance can be obtained by a careful control of shape and dopant position. These results pave the way for contact resistance engineering in forthcoming device generations.
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