scispace - formally typeset
Search or ask a question
Topic

Quantum capacitance

About: Quantum capacitance is a research topic. Over the lifetime, 954 publications have been published within this topic receiving 24165 citations.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a unified and compact classification of single negative electromagnetic metamaterial-based perfect transmission unit cells is proposed, and the classes are named as: type-A, -B and -C unit cells.
Abstract: In this article, at first we propose a unified and compact classification of single negative electromagnetic metamaterial-based perfect transmission unit cells. The classes are named as: type-A, -B and -C unit cells. Then based on the classification, we have extended these ideas in semiconductor and graphene regimes. For type-A: Based on the idea of electromagnetic Spatial Average Single Negative bandgap, novel bandgap structures have been proposed for electron transmission in semiconductor heterostructures. For type-B: with dielectric-graphene-dielectric structure, almost all angle transparency is achieved for both polarizations of electromagnetic wave in the terahertz frequency range instead of the conventional transparency in the microwave frequency range. Finally the application of the gated dielectric-graphene-dielectric has been demonstrated for the modulation and switching purpose.

7 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed an inclusive model for top-gated doped graphene field effect transistor (GFET), which is concise and accurate for calculations of the electrical parameters that are used in digital circuit design.
Abstract: In this letter, we have developed an inclusive model for top-gated doped graphene field-effect transistor (GFET). The proposed model is concise and accurate for calculations of the electrical parameters that are used in digital circuit design. The doping in single layer graphene sheet is one of the ways to create a bandgap as well as to introduce the threshold voltage (VTH) concept in GFET. Further, the modelled expressions are used for estimation of quantum capacitance (Cq), which is used for the modelling of drain current (ID), small-signal transconductance gain (gm), output resistance (ro), and figures of merit such as intrinsic voltage gain (AV), transconductance efficiency (gm/ID), and cut-off frequency (fT).

7 citations

Journal ArticleDOI
TL;DR: A novel characterization of topological phase in Bi2Se3 nanowire via nanomechanical resonance measurements shows the expected oscillations of Aharonov–Bohm conductance oscillations, and a model based on the gapless Dirac fermion with impurity scattering explains the observed quantum oscillations successfully.
Abstract: The discovery of two-dimensional gapless Dirac fermions in graphene and topological insulators (TI) has sparked extensive ongoing research toward applications of their unique electronic properties. The gapless surface states in three-dimensional insulators indicate a distinct topological phase of matter with a non-trivial Z2 invariant that can be verified by angle-resolved photoemission spectroscopy or magnetoresistance quantum oscillation. In TI nanowires, the gapless surface states exhibit Aharonov-Bohm (AB) oscillations in conductance, with this quantum interference effect accompanying a change in the number of transverse one-dimensional modes in transport. Thus, while the density of states (DOS) of such nanowires is expected to show such AB oscillation, this effect has yet to be observed. Here, we adopt nanomechanical measurements that reveal AB oscillations in the DOS of a topological insulator. The TI nanowire under study is an electromechanical resonator embedded in an electrical circuit, and quantum capacitance effects from DOS oscillation modulate the circuit capacitance thereby altering the spring constant to generate mechanical resonant frequency shifts. Detection of the quantum capacitance effects from surface-state DOS is facilitated by the small effective capacitances and high quality factors of nanomechanical resonators, and as such the present technique could be extended to study diverse quantum materials at nanoscale.

7 citations

Dissertation
31 Jul 2015
Abstract: In the past few years, led by graphene, a large variety of two dimensional (2D) materials have been discovered to exhibit astonishing properties. By assembling 2D materials with different designs, we are able to construct novel artificial van der Waals (vdW) heterostructures to explore new fundamental physics and potential applications for future technology.This thesis describes several novel vdW heterostructures and their fundamental properties. At the beginning, the basic properties of some 2D materials and assembled vdW heterostructures are introduced, together with the fabrication procedure and transport measurement setups. Then the graphene based capacitors on hBN (hexagonal Boron Nitride) substrate are studied, where quantum capacitance measurements are applied to determine the density of states and many body effects. Meanwhile, quantum capacitance measurement is also used to search for alternative substrates to hBN which allow graphene to exhibit micrometer-scale ballistic transport. We found that graphene placed on top of MoS2 and TaS2 show comparable mobilities up to 60,000cm2/Vs. After that, the graphene/hBN superlattices are studied. With a Hall bar structure based on the superlattices, we find that new Dirac minibands appear away from the main Dirac cone with pronounced peaks in the resistivity and are accompanied by reversal of the Hall effects. With the capacitive structure based on the superlattices, quantum capacitance measurement is used to directly probe the density states in the graphene/hBN superlattices, and we observe a clear replica spectrum, the Hofstadter-butterfly fan diagram, together with the suppression of quantum Hall Ferromagnetism. In the final part, we report on the existence of the valley current in the graphene/hBN superlattice structure. The topological current originating from graphene?s two valleys flows in opposite directions due to the broken inversion symmetry in the graphene/hBN superlattice, meaning an open band gap in graphene.

7 citations

Journal ArticleDOI
TL;DR: In this article, the electronic structure of bilayer graphene, where one of the layers possesses monovacancies, was studied under an external electric field using density functional theory, and it was shown that Fermi-level pinning occurs in the bilayer graph with defects under hole doping.
Abstract: The electronic structure of bilayer graphene, where one of the layers possesses monovacancies, is studied under an external electric field using density functional theory. Our calculations show that Fermi-level pinning occurs in the bilayer graphene with defects under hole doping. However, under electron doping, the Fermi level rapidly increases at the critical gate voltage with an increasing electron concentration. In addition to the carrier species, the relative arrangement of the gate electrode to the defective graphene layer affects the Fermi energy position with respect to the carrier concentration. Because the distribution of the accumulated carrier depends on the electrode position, the quantum capacitance of bilayer graphene with defects depends on the electrode position.

7 citations


Network Information
Related Topics (5)
Silicon
196K papers, 3M citations
85% related
Quantum dot
76.7K papers, 1.9M citations
85% related
Band gap
86.8K papers, 2.2M citations
85% related
Graphene
144.5K papers, 4.9M citations
83% related
Thin film
275.5K papers, 4.5M citations
83% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202331
202238
202162
202062
201965
201858