Source/Drain Asymmetry in InGaAs Vertical Nanowire MOSFETs
This work demonstrates InGaAs vertical nanowire MOSFETs fabricated via an improved top-down approach that feature comparable performance to the best bottom-up devices in terms of the balance between transport and electrostatics. These devices, when contrasted with an earlier generation fabricated by a similar technology, have enabled the first experimental study of source/drain asymmetry in InGaAs vertical nanowire MOSFETs. The transconductance differs significantly when swapping source and drain due to inherently different top and bottom contact electrical resistance. This also results in distinct asymmetry in the saturation behavior of the output characteristics. On the other hand, diameter non-uniformity along the nanowire length is responsible for asymmetry in the subthreshold characteristics. A uniform nanowire cross-section, enabled by our improved InGaAs dry etch technology in the present devices, eliminates the asymmetry of the electrostatics that was observed in our previous work.