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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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Journal ArticleDOI
TL;DR: In this article, the intrinsic effects of the band-gap opening on ballistic electron transport in graphene nanoribbons and bilayer graphenes were studied based on a computational approach, and the ultimate device performances of FETs with those semiconducting graphene channels were discussed.
Abstract: Although a graphene is a zero-gap semiconductor, band-gap energy values up to several hundred millielectronvolts have been introduced by utilizing quantum-mechanical confinement in nanoribbon structures or symmetry breaking between two carbon layers in bilayer graphenes (BLGs). However, the opening of a band gap causes a significant reduction in carrier velocity due to the modulation of band structures in their low-energy spectra. In this paper, we study intrinsic effects of the band-gap opening on ballistic electron transport in graphene nanoribbons (GNRs) and BLGs based on a computational approach, and discuss the ultimate device performances of FETs with those semiconducting graphene channels. We have shown that an increase in the external electric field in BLG-FETs to obtain a larger band-gap energy degrades substantially its electrical characteristics because of deacceleration of electrons due to a Mexican hat structure; therefore, GNR-FETs outperform in principle BLG-FETs.

19 citations

Journal ArticleDOI
03 Sep 2018
TL;DR: The field effect detection of ion channel activity within neuron networks, cultured during several weeks above graphene transistor arrays is shown and the ion gating of a single grain boundary in liquid affects the electronic transmission of the whole transistor channel, resulting in significant conductance variations.
Abstract: Graphene, the atomically-thin honeycomb carbon lattice, is a highly conducting 2D material whose exposed electronic structure offers an ideal platform for chemical and biological sensing. Its biocompatible, flexible and chemically inert nature associated with the lack of dangling bonds, offers novel perspectives for direct interfacing with biological molecules. Combined with its exceptional electronic and optical properties, this promotes graphene as a unique platform for bioelectronics. Among the successful bio-integrations of graphene, the detection of action potentials in numerous electrogenic cells including neurons has paved the road for the high spatio-temporal and wide-field mapping of neuronal activity. Ultimate resolution of sensing ion channel activity can be achieved with neural interfaces, and it was shown that macroscale electrodes can record extracellular current of individual ion channels in model systems, by charging the quantum capacitance of large graphene monolayer (mm2). Here, we show the field effect detection of ion channel activity within neuron networks, cultured during several weeks above graphene transistor arrays. Dependences upon drugs, reference potential gating and device geometry confirm the field effect detection of individual ion channel and suggest a significant contribution of grain boundaries, which provide highly sensitive nanoscale-sized sensing sites. Our theoretical analysis and simulations demonstrate that the ion gating of a single grain boundary in liquid affects the electronic transmission of the whole transistor channel, resulting in significant conductance variations. Monitoring the ion channels activity is of great interest as most of neurodegenerative diseases relied on channelopathies, which rely on ion channel abnormal activity. Thus, such highly sensitive and biocompatible neuro-electronics which open the way to FET detection at the sub-cell precision should be useful for a wide range of fundamental and applied research areas, including brain-on-chip, pharmacology, and in vivo monitoring or diagnosis.

19 citations

Journal ArticleDOI
TL;DR: In this article, a physics-based compact model for 2D field effect transistors (FETs) based on monolayer semiconductors such as MoS2 is presented.
Abstract: We present a physics-based compact model for two-dimensional (2D) field-effect transistors (FETs) based on monolayer semiconductors such as MoS2. A semi-classical transport approach is appropriate for the 2D channel, enabling simplified analytical expressions for the drain current. In addition to intrinsic FET behavior, the model includes contact resistance, traps and impurities, quantum capacitance, fringing fields, high-field velocity saturation and self-heating, the latter being found to play a strong role. The model is calibrated with state-of-the-art experimental data for n- and p-type 2D-FETs, and it can be used to analyze device properties for sub-100 nm gate lengths. Using the experimental fit, we demonstrate feasibility of circuit simulations using properly scaled devices. The complete model is implemented in SPICE-compatible Verilog-A, and a downloadable version is freely available on the nanoHUB.org.

19 citations

Journal ArticleDOI
TL;DR: A theoretical framework based on the effective screening medium and reference interaction site model is applied to explore the role of electrical double-layer (EDL) formation and its interplay with quantum capacitance in graphene-based supercapacitors, highlighting a complex interplay among surface morphology, electronic structure, and interfacial capacitance.
Abstract: Understanding and controlling the electrical response at a complex electrode–electrolyte interface is key to the development of next-generation supercapacitors and other electrochemical devices. In this work, we apply a theoretical framework based on the effective screening medium and reference interaction site model to explore the role of electrical double-layer (EDL) formation and its interplay with quantum capacitance in graphene-based supercapacitors. In addition to pristine graphene, we investigate a novel C60-modified graphene supercapacitor material, which promises higher charge-storage capacity. Beyond the expected enhancement in the quantum capacitance, we find that the introduction of C60 molecules significantly alters the EDL response. These changes in EDL are traced to the interplay between surface morphology and charge localization character and ultimately dominate the overall capacitive improvement in the hybrid system. Our study highlights a complex interplay among surface morphology, elect...

19 citations

Journal ArticleDOI
TL;DR: Graphene technology is paves the way towards the exploitation of graphene technology to become the core of active analogue phase shifters for high-frequency operation.
Abstract: We present a graphene-based phase shifter for radio-frequency (RF) phase-array applications. The core of the designed phase-shifting system consists of a graphene field-effect transistor (GFET) used in a common source amplifier configuration. The phase of the RF signal is controlled by exploiting the quantum capacitance of graphene and its dependence on the terminal transistor biases. In particular, by independently tuning the applied gate-to-source and drain-to-source biases, we observe that the phase of the signal, in the super-high frequency band, can be varied nearly 200° with a constant gain of 2.5 dB. Additionally, if only the gate bias is used as control signal, and the drain is biased linearly dependent on the former (i.e., in a completely analogue operation), a phase shift of 85° can be achieved making use of just one transistor and keeping a gain of 0 dB with a maximum variation of 1.3 dB. The latter design can be improved by applying a balanced branch-line configuration showing to be competitive against other state-of-the-art phase shifters. This work paves the way towards the exploitation of graphene technology to become the core of active analogue phase shifters for high-frequency operation.

19 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202331
202238
202162
202062
201965
201858