Title
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Tensile strained Ge tunnel field-effect transistors: material modeling and numerical device simulation
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Author
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Abstract
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Group IV based tunnel field-effect transistors generally show lower on-current than III-V based devices because of the weaker phonon-assisted tunneling transitions in the group IV indirect bandgap materials. Direct tunneling in Ge, however, can be enhanced by strain engineering. In this work, we use a 30-band k.p method to calculate the band structure of biaxial tensile strained Ge and then extract the bandgaps and effective masses at Gamma and L symmetry points in k-space, from which the parameters for the direct and indirect band-to-band tunneling (BTBT) models are determined. While transitions from the heavy and light hole valence bands to the conduction band edge at the L point are always bridged by phonon scattering, we highlight a new finding that only the light-holelike valence band is strongly coupling to the conduction band at the Gamma point even in the presence of strain based on the 30-band k.p analysis. By utilizing a Technology Computer Aided Design simulator equipped with the calculated band-to-band tunneling BTBT models, the electrical characteristics of tensile strained Ge point and line tunneling devices are self-consistently computed considering multiple dynamic nonlocal tunnel paths. The influence of field-induced quantum confinement on the tunneling onset is included. Our simulation predicts that an on-current up to 160 (260) mu A/mu m can be achieved along with on/off ratio > 10(6) for V-DD = 0.5V by the n-type (p-type) line tunneling device made of 2.5% biaxial tensile strained Ge. (C) 2014 AIP Publishing LLC. |
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Language
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English
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Source (journal)
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Journal of applied physics / American Institute of Physics. - New York, N.Y., 1937, currens
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Publication
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New York, N.Y.
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American Institute of Physics
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2014
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ISSN
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0021-8979
[print]
1089-7550
[online]
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DOI
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10.1063/1.4862806
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Volume/pages
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115
:4
(2014)
, p. 1-8
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Article Reference
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044505
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ISI
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000331210800113
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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