scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Quantum capacitance devices

08 Feb 1988-Applied Physics Letters (American Institute of Physics)-Vol. 52, Iss: 6, pp 501-503
TL;DR: In this paper, a two-dimensional electron gas (2DEG) in a quantum well or inversion layer, unlike an ordinary grounded metallic plane, does not completely screen an applied transverse electric field, but partial penetration of an external field through a highly conducting 2DEG allows the implementation of several novel high-speed devices, including a threeterminal resonant tunneling transistor and a gate-controlled thermionic emission transistor.
Abstract: Two‐dimensional electron gas (2DEG) in a quantum well or inversion layer, unlike an ordinary grounded metallic plane, does not completely screen an applied transverse electric field. Owing to its Fermi degeneracy energy, a 2DEG manifests itself as a capacitor in series, whose capacitance per unit area equals CQ=me2/πℏ2, where m is the effective electron mass in the direction transverse to the quantum well. Partial penetration of an external field through a highly conducting 2DEG allows the implementation of several novel high‐speed devices, including a three‐terminal resonant‐tunneling transistor and a gate‐controlled thermionic emission transistor.
Citations
More filters
Journal ArticleDOI
24 Feb 2012-Science
TL;DR: A bipolar field-effect transistor that exploits the low density of states in graphene and its one-atomic-layer thickness is reported, which has potential for high-frequency operation and large-scale integration.
Abstract: An obstacle to the use of graphene as an alternative to silicon electronics has been the absence of an energy gap between its conduction and valence bands, which makes it difficult to achieve low power dissipation in the OFF state We report a bipolar field-effect transistor that exploits the low density of states in graphene and its one-atomic-layer thickness Our prototype devices are graphene heterostructures with atomically thin boron nitride or molybdenum disulfide acting as a vertical transport barrier They exhibit room-temperature switching ratios of ≈50 and ≈10,000, respectively Such devices have potential for high-frequency operation and large-scale integration

2,401 citations

Journal ArticleDOI
TL;DR: In this paper, the authors review the recent progress and challenges of 2D van der Waals interactions and offer a perspective on the exploration of 2DLM-based vdWHs for future application in electronics and optoelectronics.
Abstract: Two-dimensional layered materials (2DLMs) have been a central focus of materials research since the discovery of graphene just over a decade ago. Each layer in 2DLMs consists of a covalently bonded, dangling-bond-free lattice and is weakly bound to neighbouring layers by van der Waals interactions. This makes it feasible to isolate, mix and match highly disparate atomic layers to create a wide range of van der Waals heterostructures (vdWHs) without the constraints of lattice matching and processing compatibility. Exploiting the novel properties in these vdWHs with diverse layering of metals, semiconductors or insulators, new designs of electronic devices emerge, including tunnelling transistors, barristors and flexible electronics, as well as optoelectronic devices, including photodetectors, photovoltaics and light-emitting devices with unprecedented characteristics or unique functionalities. We review the recent progress and challenges, and offer our perspective on the exploration of 2DLM-based vdWHs for future application in electronics and optoelectronics. With a dangling-bond-free surface, two dimensional layered materials (2DLMs) can enable the creation of diverse van der Waals heterostructures (vdWHs) without the conventional constraint of lattice matching or process compatibility. This Review discusses the recent advances in exploring 2DLM vdWHs for future electronics and optoelectronics.

1,850 citations

Journal ArticleDOI
21 Jun 2013-Science
TL;DR: Band structure engineering in a van der Waals heterostructure composed of a monolayer graphene flake coupled to a rotationally aligned hexagonal boron nitride substrate is demonstrated, resulting in an unexpectedly large band gap at charge neutrality.
Abstract: van der Waals heterostructures constitute a new class of artificial materials formed by stacking atomically thin planar crystals. We demonstrated band structure engineering in a van der Waals heterostructure composed of a monolayer graphene flake coupled to a rotationally aligned hexagonal boron nitride substrate. The spatially varying interlayer atomic registry results in both a local breaking of the carbon sublattice symmetry and a long-range moire superlattice potential in the graphene. In our samples, this interplay between short- and long-wavelength effects resulted in a band structure described by isolated superlattice minibands and an unexpectedly large band gap at charge neutrality. This picture is confirmed by our observation of fractional quantum Hall states at ± 5 3 filling and features associated with the Hofstadter butterfly at ultrahigh magnetic fields.

1,454 citations

Journal ArticleDOI
TL;DR: In this paper, numerical simulations are used to guide the development of a simple analytical theory for ballistic field-effect transistors, and the model reduces to Natori's theory of the ballistic MOSFET.
Abstract: Numerical simulations are used to guide the development of a simple analytical theory for ballistic field-effect transistors. When two-dimensional (2-D) electrostatic effects are small (and when the insulator capacitance is much less than the semiconductor (quantum) capacitance), the model reduces to Natori's theory of the ballistic MOSFET. The model also treats 2-D electrostatics and the quantum capacitance limit where the semiconductor quantum capacitance is much less than the insulator capacitance. This new model provides insights into the performance of MOSFETs near the scaling limit and a unified framework for assessing and comparing a variety of novel transistors.

740 citations


Cites background or methods from "Quantum capacitance devices"

  • ...In Section V, we apply the new model to ideal carbon nanotube FETs and discuss the interesting effects that occur in the quantum capacitance limit [26]....

    [...]

  • ...charge, this effect can be described by a nonlinear quantum capacitance [26]....

    [...]

Journal ArticleDOI
TL;DR: In this article, a resonant tunnelling of Dirac fermions through a boron nitride barrier, a few atomic layers thick, sandwiched between two graphene electrodes is described.
Abstract: The chemical stability of graphene and other free-standing two-dimensional crystals means that they can be stacked in different combinations to produce a new class of functional materials, designed for specific device applications. Here we report resonant tunnelling of Dirac fermions through a boron nitride barrier, a few atomic layers thick, sandwiched between two graphene electrodes. The resonance occurs when the electronic spectra of the two electrodes are aligned. The resulting negative differential conductance in the device characteristics persists up to room temperature and is gate voltage-tuneable due to graphene’s unique Dirac-like spectrum. Although conventional resonant tunnelling devices comprising a quantum well sandwiched between two tunnel barriers are tens of nanometres thick, the tunnelling carriers in our devices cross only a few atomic layers, offering the prospect of ultra-fast transit times. This feature, combined with the multi-valued form of the device characteristics, has potential for applications in high-frequency and logic devices.

586 citations

References
More filters
Journal ArticleDOI
TL;DR: In this paper, the electronic properties of inversion and accumulation layers at semiconductor-insulator interfaces and of other systems that exhibit two-dimensional or quasi-two-dimensional behavior, such as electrons in semiconductor heterojunctions and superlattices and on liquid helium, are reviewed.
Abstract: The electronic properties of inversion and accumulation layers at semiconductor-insulator interfaces and of other systems that exhibit two-dimensional or quasi-two-dimensional behavior, such as electrons in semiconductor heterojunctions and superlattices and on liquid helium, are reviewed. Energy levels, transport properties, and optical properties are considered in some detail, especially for electrons at the (100) silicon-silicon dioxide interface. Other systems are discussed more briefly.

5,638 citations

Journal ArticleDOI
Yusuke Ota1
TL;DR: The silicon molecular beam epitaxy (MBE) technique has only been used in silicon device applications in the last 5 years as discussed by the authors, and it is expected that in the near future silicon MBE will be applied to a much wider range of silicon devices including silicon integrated circuits.

299 citations

Book
01 Oct 1987
TL;DR: In this article, the energy gap theory of solids has been studied in the context of semiconductors and photo-electronic devices, and the energy band theory has been proposed.
Abstract: Keywords: Semiconductors ; Junctions ; Photoelectronic devices ; Energy-band theory of solids ; Energy gap (Physics) Reference LSE-BOOK-1987-001 Record created on 2006-10-03, modified on 2017-05-12

220 citations

Journal ArticleDOI
TL;DR: In this paper, the relative positions of the base and collector are interchanged from conventional emitter-base-collector sequence to obtain negligible base currents and large current transfer ratios.
Abstract: Two novel three‐terminal devices based on tunneling in quantum well and quantum barrier heterostructures are proposed and analyzed theoretically. In both devices, the relative positions of the base and collector are interchanged from conventional emitter‐base‐collector sequence. This provides a means for obtaining negligible base currents and large current transfer ratios. In both cases, a base voltage controls the emitter‐collector tunneling current by shifting the resonances in a quantum well. Calculations indicate that significant variations in the emitter‐collector current‐voltage characteristics can be obtained for reasonable base‐emitter voltages. We call the two devices a Stark effect transistor and a negative resistance Stark effect transistor, respectively.

72 citations

Journal ArticleDOI
TL;DR: In this article, a three-dimensional perturbation-theory treatment of the carrier-density fluctuations in the insulated gate field effect transistor (IGFET) above threshold and their effect upon the source-drain current is presented.
Abstract: A three‐dimensional perturbation‐theory treatment of the carrier‐density fluctuations in the insulated‐gate field‐effect transistor (IGFET) above threshold and their effect upon the source‐drain current is presented. The fluctuations are considered to be generated by interface charge nonuniformities. It is shown that such fluctuations reduce the source‐drain current over that for a uniform device with the same average carrier density. It is found that the fluctuations increase with decreasing carrier density, that they are larger in a shallow channel than in a deep channel, and that the increase in fluctuations with decreasing carrier density is quite abrupt. The critical carrier density below which carrier‐density fluctuations are important is found to be ?1011 carriers/cm2 at 300 °K and ?1012 carriers/cm2 at 0 °K for ordinary‐device charge densities. The difference in the threshold for the onset of fluctuations at the two temperatures is attributable to the smaller amplitude of fluctuations at high temp...

70 citations