Tensile Strained Ge Tunnel Field-Effect Transistors: K . P Material Modeling and Numerical Device Simulation

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Tensile Strained Ge Tunnel Field-Effect Transistors: K . P Material Modeling and Numerical Device Simulation

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Title: Tensile Strained Ge Tunnel Field-Effect Transistors: K . P Material Modeling and Numerical Device Simulation
Author(s):
Kao, Kuo-Hsing;
Verhulst, Anne S.;
Van de Put, Maarten;
Vandenberghe, William G. H.;
Soree, Bart;
Magnus, Wim;
De Meyer, Kristin
Format: text
Item Type: article
Keywords: Germanium
Silicon
Field-effect transistors (FET)
Physics
Abstract: 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 Γ 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 Γ 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) μA/μm 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.
Publisher: Amer Inst Physics
ISSN: 0021-8979
Persistent Link: http://dx.doi.org/10.1063/1.4862806
http://hdl.handle.net/10735
Terms of Use: ©2014 AIP Publishing LLC

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