Quantum capacitance in nanoscale device modeling

John, D.L.; Castro, L. C.; Pulfrey, D.L.

doi:10.1063/1.1803614

Cited by 320 publications

(181 citation statements)

References 16 publications

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“…This result agrees with the common value 4 pF/cm Q C = usually considered in a (metallic) CNT with one occupied subband [28]. The weak field observed in the channel can also be related to highly ballistic transport as mentioned above.…”

Section: Ds V =supporting

confidence: 81%

Influence of capacitive effects on the dynamic of a CNTFET by Monte Carlo method

d'Honincthun¹,

Nguyen²,

Galdin‐Retailleau³

et al. 2008

Physica E: Low-dimensional Systems and Nanostructures

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Carbon Nanotube (CNT) appears as a promising candidate to shrink field-effect transistors (FET) to the nanometer scale. Extensive experimental works have been performed recently to develop the appropriate technology and to explore DC characteristics of carbon nanotube field effect transistor (CNTFET). In this work, we present results of Monte Carlo simulation of a coaxially gated CNTFET including electron-phonon scattering. Our purpose is to present the intrinsic transport properties of such material through the evaluation of electron mean-free-path. To highlight the potential of high performance level of CNTFET, we then perform a study of DC characteristics and of the impact of capacitive effects. Finally, we compare the performance of CNTFET with that of Si nanowire MOSFET. RésuméInfluence des effets capacitifs sur les performances dynamiques d'un CNTFET par la méthode Monte Carlo. Le nanotube de carbone (CNT) est à ce jour l'un des candidats les plus prometteurs pour faire passer le transistor à effet de champ (FET) à l'échelle du nanomètre. Des recherches intensives sont en cours afin de déterminer les caractéristiques statiques et dynamiques des transistors à nanotube de carbone (CNTFET). Nous présentons dans cette étude des résultats de simulations de CTNFET par la méthode Monte-Carlo avec prise en compte des interactions électrons-phonons. Un des objectifs est de présenter les propriétés du transport pouvant être atteintes dans ce matériau par une évaluation du libre parcours moyen des porteurs. Une étude des caractéristiques statiques du CNTFET est réalisée et permet de mettre en avant l'influence du 2 contrôle capacitif par la grille sur les performances. Enfin nous comparons les performances d'un CNTFET avec celles obtenues par simulation d'un transistor à nanofil de Silicium.

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Section: Ds V =supporting

confidence: 81%

Influence of capacitive effects on the dynamic of a CNTFET by Monte Carlo method

d'Honincthun¹,

Nguyen²,

Galdin‐Retailleau³

et al. 2008

Physica E: Low-dimensional Systems and Nanostructures

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“…The switching time of a nanoscale optical modulator is limited by the quantum capacitance, C q ¼ @Q=@V a , where Q is the charge density and V a is the local electrostatic potential [27][28][29]. Figure 3(d) plots the transient rise time of optical modulation of the pristine film (SF-4) subjected to an electric field of 20 V=cm, from which an effective capacitance can be calculated C=C q ¼ 6 Â 10 3 .…”

Section: Prl 102 047402 (2009) P H Y S I C a L R E V I E W L E T T Ementioning

confidence: 99%

Unusually Large Franz-Keldysh Oscillations at Ultraviolet Wavelengths in Single-Walled Carbon Nanotubes

et al. 2009

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We report large electroabsorption susceptibilities in the ultraviolet region for single-walled carbon nanotubes (SWNT) supported on quartz that are approximately 10 3 larger than the highest values reported to date for any system. The oscillatory behavior is described using a convolution of Airy functions in photon energy ascribing the effect to Franz-Keldysh oscillations. The metallic and semiconducting SWNT composition is varied, and it is shown that the confinement energy correlates with the average band gap for semiconducting SWNT in the film. The large susceptibilities arise from a subpercolated network of metallic SWNT that enhances the local electric field. DOI: 10.1103/PhysRevLett.102.047402 PACS numbers: 78.67.Ch, 78.20.Jq, 78.40.Ri, 78.66.Tr Semiconducting single-walled carbon nanotubes (SWNT) have attracted significant attention recently due to many unique properties and the potential for new nanophotonic applications [1]. They possess sharp singularities in their density of states as a consequence of onedimensional (1D) quantum confinement leading to strong and discrete absorption maxima throughout the ultraviolet (UV), visible, and near-infrared (IR) regions of the electromagnetic spectrum [2,3]. This confinement also leads to theoretical predictions of large exciton binding energies, later confirmed using two photon photoluminescence spectroscopy [4,5]. Franz-Keldysh (FK) oscillations, in particular, are calculated [6] to be quite strong for semiconducting SWNT near the first and second band edge, a property of importance for electro-optical applications. In pioneering work several decades ago, Franz and Keldysh predicted that photo-excited electrons could tunnel into an otherwise classically forbidden energy gap under the influence of an electric field, modifying the linear optical properties of bulk semiconductors near the absorption band edge [7,8]. Modulation spectroscopy uses this effect experimentally to understand highly localized electric fields that develop at semiconductor interfaces [9,10]. Nanowires and nanotubes can amplify such fields manyfold by virtue of their geometry. Hence, there is interest in using phenomena such as the FK effect to understand how electric fields can be manipulated on the nanometer scale, although to date, no experimental observation of the effect has been reported for any of the carbon family of nanomaterials.In this Letter, we report the first observation of FK oscillations for semiconducting SWNT films supported on fused quartz substrates, although the effect is strongest for excitonic states much higher than those near the band edge. Electroabsorption susceptibilities in the UV region are more than 10 3 larger than the highest values reported for typical semiconductor systems, such as III-V semiconductors [9] and semiconductor-doped glasses [11]. We make use of recent progress [12] in the enrichment of metallic and semiconducting SWNT to show that the confinement energy correlates with the average band gap for semiconducting SWNT in the film. The unusua...

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“…3 illustrates the intrinsic parameters for our device. The oscillatory peaks in the capacitances and transconductance are related to the formation of quasi-bound states in the short channel [7,9]. With the modulation of the applied voltage, the states, indicated by the bright patches in Fig.…”

Section: Resultsmentioning

confidence: 95%

High-Frequency Capability of Schottky-Barrier Carbon Nanotube FETs

Castro

Pulfrey

John

2007

SSP

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Abstract. The high-frequency capability of carbon nanotube field-effect transistors is investigated by simulating the small-signal performance of a device with negative-barrier Schottky contacts for the source and drain, and with a small, ungated region of nanotube between the end contacts and the edge of the wrap-around gate electrode. The overall structure is shown to exhibit resonant behaviour, which leads to a significant bias dependence of the small-signal capacitances and transconductance. This could lead to high-frequency figures of merit (f T and f max ) in the terahertz regime.

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Quantum capacitance in nanoscale device modeling

Cited by 320 publications

References 16 publications

Influence of capacitive effects on the dynamic of a CNTFET by Monte Carlo method

Influence of capacitive effects on the dynamic of a CNTFET by Monte Carlo method

Unusually Large Franz-Keldysh Oscillations at Ultraviolet Wavelengths in Single-Walled Carbon Nanotubes

High-Frequency Capability of Schottky-Barrier Carbon Nanotube FETs

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