Modeling of carrier density and quantum capacitance in graphene nanoribbon FETs

Kliros, George S.

doi:10.1109/icm.2010.5696126

Cited by 9 publications

(6 citation statements)

References 16 publications

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“…As can be seen from the plot, the quantum capacitance increases linearly with the increase of strain. The obtained small values of the quantum capacitance at lower strain are attributed to low DOS characterization of the atomically thin quasi 1D channel [ 27 ]; the further reduction of the DOS is due to quantum confinement boundary conditions in the AGNRs' transverse direction. It is also important to note that the quantum capacitance significantly increases with the decrease in the size of ribbon width, which is a direct consequence of energy bandgap widening.…”

Section: Resultsmentioning

confidence: 99%

Analytical performance of 3 m and 3 m + 1 armchair graphene nanoribbons under uniaxial strain

Kang

Ismail

2014

Nanoscale Res Lett

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The electronic band structure and carrier density of strained armchair graphene nanoribbons (AGNRs) with widths of n =3 m and n =3 m +1 were examined using tight-binding approximation. The current-voltage (I-V) model of uniaxial strained n =3 m AGNRs incorporating quantum confinement effects is also presented in this paper. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on a tight-binding approximation. Our results reveal the modification of the energy bandgap, carrier density, and drain current upon strain. Unlike the two-dimensional graphene, whose bandgap remains near to zero even when a large strain is applied, the bandgap and carrier density of AGNRs are shown to be sensitive to the magnitude of uniaxial strain. Discrepancies between the classical calculation and quantum calculation were also measured. It has been found that as much as 19% of the drive current loss is due to the quantum confinement. These analytical models which agree well with the experimental and numerical results provide physical insights into the characterizations of uniaxial strained AGNRs.

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Section: Resultsmentioning

confidence: 99%

Analytical performance of 3 m and 3 m + 1 armchair graphene nanoribbons under uniaxial strain

Kang

Ismail

2014

Nanoscale Res Lett

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“…As it can be seen from the plot, quantum capacitance increases linearly with the increment of strain. The obtained small values of quantum capacitance at lower strain are attributed to low DOS characterization of the atomically thin quasi-1D channel [22] and further reduction of the DOS due to quantum confinement boundary conditions in the AGNRs transverse direction. It is also important to notice that the quantum capacitance significantly increases with the decrement in the size of ribbon width which is a direct consequence of energy band gap widening.…”

Section: Resultsmentioning

confidence: 92%

Unified Drain Current Model of Armchair Graphene Nanoribbons with Uniaxial Strain and Quantum Effect

Kang

Ismail

2014

Journal of Nanomaterials

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A unified current-voltageI-Vmodel of uniaxial strained armchair graphene nanoribbons (AGNRs) incorporating quantum confinement effects is presented in this paper. TheI-Vmodel is enhanced by integrating both linear and saturation regions into a unified and precise model of AGNRs. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on the tight-binding approximation. Our results reveal the modification of the energy band gap, carrier density, and drain current upon strain. The effects of quantum confinement were investigated in terms of the quantum capacitance calculated from the broadening density of states. The results show that quantum effect is greatly dependent on the magnitude of applied strain, gate voltage, channel length, and oxide thickness. The discrepancies between the classical calculation and quantum calculation were also measured and it has been found to be as high as 19% drive current loss due to the quantum confinement. Our finding which is in good agreement with the published data provides significant insight into the device performance of uniaxial strained AGNRs in nanoelectronic applications.

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“…Considering the electrostatics describing the structure, the following relation between the gate voltage and Fermi energy E F can be obtained [ 33 ]…”

Section: Methodsmentioning

confidence: 99%

“…The quantum capacitance describes the change in channel charge due to a given change in gate voltage and can be calculated by C Q = q 2 ∂ n 1D / ∂ E F where q is the electron charge and n 1D is the one-dimensional electron density [ 33 ]. Using Equation (6) and writing in terms of Fermi integrals of order (−3/2), we obtain [ 26 ]…”

Section: Methodsmentioning

confidence: 99%

Analytical modeling of uniaxial strain effects on the performance of double-gate graphene nanoribbon field-effect transistors

Kliros

2014

Nanoscale Res Lett

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The effects of uniaxial tensile strain on the ultimate performance of a dual-gated graphene nanoribbon field-effect transistor (GNR-FET) are studied using a fully analytical model based on effective mass approximation and semiclassical ballistic transport. The model incorporates the effects of edge bond relaxation and third nearest neighbor (3NN) interaction. To calculate the performance metrics of GNR-FETs, analytical expressions are used for the charge density, quantum capacitance, and drain current as functions of both gate and drain voltages. It is found that the current under a fixed bias can change several times with applied uniaxial strain and these changes are strongly related to strain-induced changes in both band gap and effective mass of the GNR. Intrinsic switching delay time, cutoff frequency, and Ion/Ioff ratio are also calculated for various uniaxial strain values. The results indicate that the variation in both cutoff frequency and Ion/Ioff ratio versus applied tensile strain inversely corresponds to that of the band gap and effective mass. Although a significant high frequency and switching performance can be achieved by uniaxial strain engineering, tradeoff issues should be carefully considered.

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Modeling of carrier density and quantum capacitance in graphene nanoribbon FETs

Cited by 9 publications

References 16 publications

Analytical performance of 3 m and 3 m + 1 armchair graphene nanoribbons under uniaxial strain

Analytical performance of 3 m and 3 m + 1 armchair graphene nanoribbons under uniaxial strain

Unified Drain Current Model of Armchair Graphene Nanoribbons with Uniaxial Strain and Quantum Effect

Analytical modeling of uniaxial strain effects on the performance of double-gate graphene nanoribbon field-effect transistors

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