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Quantum capacitance
About: Quantum capacitance is a research topic. Over the lifetime, 954 publications have been published within this topic receiving 24165 citations.
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TL;DR: In this paper, a self-contained introduction to theoretical modeling of gate-induced carrier density in graphene sheets is provided, where relevant theories are introduced, namely, classical capacitance model (CCM), self-consistent Poisson-Dirac method (PDM), and quantum capacitance models (QCM).
Abstract: This article aims at providing a self-contained introduction to theoretical modeling of gate-induced carrier density in graphene sheets. For this, relevant theories are introduced, namely, classical capacitance model (CCM), self-consistent Poisson-Dirac method (PDM), and quantum capacitance model (QCM). The usage of Matlab pdetool is also briefly introduced, pointing out the least knowledge required for using this tool to solve the present electrostatic problem. Results based on the three approaches are compared, showing that the quantum correction, which is not considered by the CCM but by the other two, plays a role only when the metal gate is exceedingly close to the graphene sheet, and that the exactly solvable QCM works equally well as the self-consistent PDM. Practical examples corresponding to realistic experimental conditions for generating graphene pnp junctions and superlattices, as well as how a background potential linear in position can be achieved in graphene, are shown to illustrate the applicability of the introduced methods. Furthermore, by treating metal contacts in the same way, the last example shows that the PDM and the QCM are able to resolve the contact-induced doping and screening potential, well agreeing with the previous first-principles studies.
2 citations
01 Dec 2011
TL;DR: In this article, an analytical model for quantum capacitance of monolayer and bilayer graphene was developed and the resistance of the channel was modelled based on conductance of the nanoribbon and finally propagation delay was calculated by using resistance and capacitance.
Abstract: Fundamental limitations of CMOS technology and anticipations of Moore's law have motivated researchers to find several alternatives for these devices such as nanowire, carbon nanotube and graphene nanoribbon [1]. In this work firstly, we develop an analytical model for quantum capacitance of monolayer and bilayer graphene. Secondly, resistance of the channel is modelled based on conductance of the nanoribbon and finally propagation delay is calculated by using resistance and capacitance.
2 citations
TL;DR: In this article, the Thouless correlation energy (Ec = ℏ/τ) is interpreted as the time constant τ = RCQ with RG ≡ 1, giving at once CQ = (e2/2π Δ) and the statistics of the quantum capacitance is directly related to that of the level spacing.
Abstract: The Thouless formula (G = (e2/h)(Ec/Δ) for the two-probe dc conductance G of a d-dimensional mesoscopic cube is re-analysed to relate its quantum capacitance CQ to the reciprocal of the level spacing Δ. To this end, the escape time-scale τ occurring in the Thouless correlation energy (Ec = ℏ/τ) is interpreted as the time constantτ = RCQ with RG ≡ 1, giving at once CQ = (e2/2π Δ). Thus, the statistics of the quantum capacitance is directly related to that of the level spacing, which is well known from the Random Matrix Theory for all the three universality classes of statistical ensembles. The basic questions of how intrinsic this quantum capacitance can arise purely quantum-resistively, and of its observability vis-a-vis the external geometric capacitance that combines with it in series, are discussed.
2 citations
TL;DR: In this paper, the quantum capacitance under strain in an external tilted magnetic field was investigated and a minimum at the charge neutrality point due to splitting of the zeroth Landau level was demonstrated.
Abstract: Topological insulators exhibit unique properties due to surface states of massless Dirac fermions with conserved time reversal symmetry. We consider the quantum capacitance under strain in an external tilted magnetic field and demonstrate a minimum at the charge neutrality point due to splitting of the zeroth Landau level. We also find beating in the Shubnikov de Haas oscillations due to strain, which originate from the topological helical states. Varying the tilting angle from perpendicular to parallel washes out these oscillations with a strain induced gap at the charge neutrality point. Our results explain recent quantum capacitance and transport experiments.
2 citations
23 Jul 2018
TL;DR: In this paper, the effects of uniaxial strain on the characteristics and performance metrics of armchair graphene nanoribbon (AGNR)-FETs are investigated utilizing an analytical quasi-ballistic transport model which accounts for several finite-size and edge effects.
Abstract: In the present work, the effects of uniaxial strain on the characteristics and performance metrics of armchair graphene nanoribbon (AGNR)-FETs are investigated utilizing an analytical quasi-ballistic transport model which accounts for several finite-size and edge effects. The model leads to an explicit expression for the current-voltage characteristics of the device with only two fitting parameters and is verified by atomistic quantum simulations. Gate capacitance, intrinsic cutoff frequency, on/off drain-current ratio and power-delay product under strain applied to the three distinct families of AGNRs, are calculated. Our study can provide some insights and guidance for strain engineering of GNR-based FETs.
2 citations