Design Space for Low Sensitivity to Size Variations in  PMOS Nanowire Devices: The Implications of Anisotropy in the Quantization Mass
Date of this Version12-3-2008
This work was funded by the Semiconductor Research Corporation (SRC). The computational resources for this work were provided through nanoHUB.org by the Network for Computational Nanotechnology (NCN). The authors ackowledge professor Timothy Boykin of University of Alabama at Huntsville for tight-binding discussions.
A 20-band sp3d5s* spin-orbit-coupled, semiempirical, atomistic tight-binding model is used with a semiclassical, ballistic, ﬁeld effect transistor (FET) model, to examine the ON-current variations to size variations of -oriented PMOS nanowire devices. Inﬁnitely long, uniform, rectangular nanowires of side dimensions from 3 to 12 nm are examined and signiﬁcantly different behavior in width versus height variations are identiﬁed and explained. Design regions are identiﬁed, which show minor ON-current variations to signiﬁcant width variations that might occur due to lack of line width control. Regions which show large ON-current variations to small height variations are also identiﬁed. The considerations of the full band model here show that ON-current doubling can be observed in the ON-state at the onset of volume inversion to surface inversion transport caused by structural side size variations. Strain engineering can smooth out or tune such sensitivities to size variations. The cause of variations described is the structural quantization behavior of the nanowires, which provide an additional variation mechanism to any other ON-current variations such as surface roughness, phonon scattering, etc.
Nanoscience and Nanotechnology