High frequency noise of epitaxial graphene grown on sapphire

Ardaravicˇius, L.; Liberis, J.; Šermukšnis, E.; Matulionis, A.; Hwang, Jeonghyun; Kwak, Joon Young; Campbell, Dorr; Alsalman, Hussain; Eastman, L.F.; Spencer, Michael G.

doi:10.1002/pssr.201307074

Cited by 6 publications

(6 citation statements)

References 18 publications

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“…63,64 Moreover, shot noise due to carriers traversing potential barriers could also have influence at least at the GHz range, as recently shown by other authors. 18…”

Section: Resultsmentioning

confidence: 99%

“…[13][14][15][16][17] Recently, high-frequency noise has been studied in graphene on sapphire, showing, in that case, the importance of shot a) Electronic mail: raulr@usal.es noise associated with hole jumps across the potential barriers located in the graphene layer. 18 An in-depth study of diffusivity in this material is also a must; in the case of bilayer graphene (which bandstructure notably differs from that of monolayer graphene 3 ), the electric field dependence of the diffusion coefficient has been studied analytically by using the relaxation time approximation (assuming a constant τ ) in order to solve the kinetic Boltzmann transport equation. 19 Other studies have been devoted to monolayer graphene, investigating by pump-probe spectroscopy the expansion of a Gaussian spatial profile of carriers; in this way, diffusion coefficients equal to 11000 and 5500 cm 2 /s in epitaxial graphene and reduced graphene-oxide samples have been observed.…”

Section: Introductionmentioning

confidence: 99%

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Diffusion coefficient, correlation function, and power spectral density of velocity fluctuations in monolayer graphene

Rengel

Martín

2013

Journal of Applied Physics

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In this paper, the diffusivity in suspended monolayer graphene at low and high electric fields is investigated. The knowledge of this quantity and its dependence on the electric field is of primary importance not only for the investigation of the electronic transport properties of this material but also for the development of accurate drift-diffusion models. The results have been obtained by means of an ensemble Monte Carlo simulation. For the calculation of the diffusion coefficient, two different methods are considered, one based on the second central moment and the other one based on the Fourier analysis of velocity fluctuations, which are directly related to the noise behaviour at high frequencies. The diffusion coefficient is analyzed considering both parallel and transversal directions with regard to the applied field. Taking into account the importance of degeneracy in this material, the calculations are properly performed by considering an excess electron population obeying a linearized Boltzmann transport equation, which allows studying in an adequate fashion the diffusivity phenomena. The results show the importance of degeneracy effects at very low fields in which transport is mainly dominated by acoustic phonon scattering. Values of the diffusion coefficient larger than 40 000 cm2/Vs are obtained for a carrier concentration equal to 1012 cm−2. The correlation function of instantaneous velocity fluctuation is explained in terms of the wavevector distribution, and their power spectral density is evaluated in the THz range, showing an important dependence on the applied field and being strongly related to microscopic transport processes.

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“…63,64 Moreover, shot noise due to carriers traversing potential barriers could also have influence at least at the GHz range, as recently shown by other authors. 18…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Diffusion coefficient, correlation function, and power spectral density of velocity fluctuations in monolayer graphene

Rengel

Martín

2013

Journal of Applied Physics

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“…Moreover, upon transferring the epitaxial graphene onto a thickness optimized SiO 2 substrate, the contrast of the layers is enhanced by the substrate interference effect. High frequency noise and transport results in graphene on sapphire [27] and SiC [28] were reported recently. There are no data on microwave noise and high-field transport on graphene grown on SiC and transferred on SiO 2 .…”

Section: Introductionmentioning

confidence: 89%

“…The results of current noise spectral density for graphene (closed circles and stars) find themselves below the ideal shot noise (2qI) defined for uncorrelated passage of carriers through barriers (empty circles) at currents up to 5 mA. This may become an important reason to observe reduced shot noise associated with carrier (hole) jumps between these barriers in the graphene layer [27]. The correlation is often estimated by the Fano factor F = S I /2qI.…”

Section: Microwave Noisementioning

confidence: 99%

“…The higher is the noise temperature (figure 6, stars; contact resistance is eliminated) the higher is the spectral density (figure 7, stars). SiC epitaxial few layer graphene 5.2 × 10 7 cm s −1 [28] 6.0 × 10 −3 [28] CVD monolayer graphene on sapphire 2.3 × 10 7 cm s −1 3.0 × 10 −3 [27] Exfoliated suspended graphene 3.6 × 10 7 cm s −1 [14] 0.25 [22] The existence of crystallite domains in graphene as AFM data shows [45] might create potential barriers for carriers. The results of current noise spectral density for graphene (closed circles and stars) find themselves below the ideal shot noise (2qI) defined for uncorrelated passage of carriers through barriers (empty circles) at currents up to 5 mA.…”

Section: Microwave Noisementioning

confidence: 99%

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Self-heating controlled current-voltage and noise characteristics in graphene

Ardaravičius¹,

Kiprijanovič²,

Alsalman³

et al. 2020

J. Phys. D: Appl. Phys.

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Pulsed current–voltage characteristics have been measured for epitaxial SiC graphene under controlled lattice temperature conditions. The monolayer and AB stacked bilayer graphene is dry transferred on SiO2. The measured characteristics of two-terminal samples with coplanar electrodes demonstrate non-ohmic behaviour up to intermediate-high fields. At high currents thermal effects come into play and soft damage of the samples takes place. Bilayer graphene samples withstand 20 kV cm−1 electric field when few nanosecond voltages pulses are applied. The results are treated in terms of hole drift velocity estimated from the data on current under the assumption of uniform electric field and constant hole density. The highest velocity of ∼3.5–5 × 106 cm s−1 (∼1.5 × 107 cm s−1) is estimated for the bilayer (monolayer) graphene. The velocity results are interpreted with hot phonons. High frequency noise is measured at 10 GHz for the monolayer graphene and the associated shot noise is resolved.

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A balance equations approach for the study of the dynamic response and electronic noise in graphene

Rengel

Iglesias

Pascual

et al. 2017

Journal of Applied Physics

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A computationally efficient modelling approach for the study of the small-signal and high-frequency noise properties of graphene is presented. The method combines stationary Monte Carlo particle simulations and analytical balance equations. Relevant parameters, like energy and velocity relaxation rates, are determined as a function of the applied electric field for graphene on several substrates of interest. The results show that transport in graphene is characterized by a streaming motion regime governed by the interplay between the applied field and the interactions with surface polar phonons. The dynamic behavior is analyzed by means of the response matrix, the time dependent velocity response functions, and the spectra and cut-off frequency of the differential mobility. It is shown that the negative differential mobility intrinsic of pure graphene could be exploited up to the THz in graphene on h-BN, SiC, SiO2, and even HfO2, with values approaching those of III-V nitrides, thus opening the possibility of graphene-based frequency multipliers, fast switches, or high frequency oscillators based on this effect. The correlation functions of velocity fluctuations and their power spectral density are also computed in order to determine the noise temperature, which shows a good agreement with complete Monte Carlo simulations, thus assuring the reliability of the proposed approach.

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High frequency noise of epitaxial graphene grown on sapphire

Cited by 6 publications

References 18 publications

Diffusion coefficient, correlation function, and power spectral density of velocity fluctuations in monolayer graphene

Diffusion coefficient, correlation function, and power spectral density of velocity fluctuations in monolayer graphene

Self-heating controlled current-voltage and noise characteristics in graphene

A balance equations approach for the study of the dynamic response and electronic noise in graphene

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