InAs nanowire-tunnel eld eect transistors (NW-TFETs) are being considered for future, beyond-Si electronics.
They oer the possibility of beating the ideal thermal limit to the inverse subthreshold slope of 60 mV/dec and
thus promise reduced power operation. However, whether the tunneling can provide sucient on-current for
high-speed operation is an open question. In this work, for a p-i-n device, we investigate the source doping
level necessary to achieve a target on-current (1 A) while maintaining a high ION=IOFF ratio (1106) for a
range of NW diameters (2 -8 nm). With a xed drain bias voltage and a maximum gate overdrive, we compare
the performance in terms of the inverse subthreshold slope (SS) and ION=IOFF ratio as a function of NW-
diameter and source doping. As expected, increasing the source doping level increases the current as a result of
the reduced screening length and increased electric eld at source which narrows the tunnel barrier. However,
since the degeneracy is also increasing, it moves the eective energy window for tunneling away from the barrier
where it is the narrowest. This, in turn, tends to decrease the current for a given voltage which, along with the
consideration of inverse SS and ION=IOFF ratio leads to an optimum choice of source doping.