Ultra-thin-body (UTB) channel materials of a few nanometers in thickness are currently considered as candidates for future electronic, thermoelectric, and optoelectronic applications. Among the features that they possess, which make them attractive for such applications, their confinement length scale, transport direction, and confining surface orientation serve as degrees of freedom for engineering their electronic properties. This work presents a comprehensive study of hole velocities in p-type UTB films of widths from 15 nm down to 3 nm. Various transport and surface orientations are considered. The atomistic sp3d5s*-spin-orbit-coupled tight-binding model is used for the electronic structure, and a semiclassical ballistic model for the carrier velocity calculation. We find that the carrier velocity is a strong function of orientation and layer thickness. The (110) and (112) surfaces provide the highest hole velocities, whereas the (100) surfaces the lowest velocities, almost 30% lower than the best performers. Additionally, up to 35% velocity enhancements can be achieved as the thickness of the (110) or (112) surface channels is scaled down to 3 nm. This originates from strong increase in the curvature of the p-type UTB film subbands with confinement, unlike the case of n-type UTB channels. The velocity behavior directly translates to ballistic on-current trends, and correlates with trends in experimental mobility measurements.
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1 March 2011
Research Article|
March 15 2011
Subband engineering for p-type silicon ultra-thin layers for increased carrier velocities: An atomistic analysis
Neophytos Neophytou;
Neophytos Neophytou
a)
1
Institute for Microelectronics
, TU Wien, Gußhausstraße 27-29/E360, A-1040 Wien, Austria
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Gerhard Klimeck;
Gerhard Klimeck
2
Network for Computational Nanotechnology, Purdue University
, Indiana 47907, USA
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Hans Kosina
Hans Kosina
b)
1
Institute for Microelectronics
, TU Wien, Gußhausstraße 27-29/E360, A-1040 Wien, Austria
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a)
Electronic mail: neophytou@iue.tuwien.ac.at.
b)
Electronic mail: kosina@iue.tuwien.ac.at.
J. Appl. Phys. 109, 053721 (2011)
Article history
Received:
July 23 2010
Accepted:
January 18 2011
Citation
Neophytos Neophytou, Gerhard Klimeck, Hans Kosina; Subband engineering for p-type silicon ultra-thin layers for increased carrier velocities: An atomistic analysis. J. Appl. Phys. 1 March 2011; 109 (5): 053721. https://doi.org/10.1063/1.3556435
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