Synthesis of graphene and other two-dimensional materials

Salazar, Norberto; Márquez, Carlos; Gámiz, F.

doi:10.1016/b978-0-12-818658-9.00006-5

Cited by 5 publications

(6 citation statements)

References 508 publications

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“…Actually, systems of this kind can be emulated in the real world. For example, this would be the case of graphene sheets and other two-dimensional materials operating as interruptors [41]- [43]. Moreover, the conclusions extracted from this work can easily be extended to other higher-dimensional structures modulated in both time and spaces.…”

Section: Introductionmentioning

confidence: 88%

“…A plane wave vibrating with period of T 0 and angular frequency ω 0 = 2π/T 0 illuminates the discontinuity. A real implementation of a system of this kind can be, for example, a graphene sheet switching between conductor and non-conductor states, controlled by an external bias voltage [41]- [43].…”

Section: Theoretical Formalismmentioning

confidence: 99%

“…The expression in (41) represents an infinite summation of impedances, translated to the circuit language as an infinite series connection. The circuit topology is actually identical to that in spatially-modulated gratings [44], despite the internal differences on the definition of the involved parameters.…”

Section: F Time-varying Surface Current At the Discontinuity And Circ...mentioning

confidence: 99%

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Time-varying Metallic Interfaces

Alex‐Amor¹,

Molero²

2022

Preprint

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This paper presents an analytical framework for the analysis of time-varying metallic metamaterials. Concretely, we particularize the study to time-modulated metallic interfaces embedded between two different semi-infinite media that are illuminated by monochromatic plane waves of frequency ω0. The formulation is based on a Floquet-Bloch modal expansion, which takes into account the time periodicity of the structure (Ts = 2π/ωs), and integral-equation techniques. It allows to extract the reflection/transmission coefficients as well as to derive nontrivial features about the dynamic response and dispersion curves of time-modulated screens. In addition, the proposed formulation has an associated equivalent circuit that gives physical insight to the diffraction phenomenon. Finally, some analytical results are presented to validate the present framework. A good agreement is observed with numerical computations provided by a self-implemented finite-difference time-domain (FDTD) method. Interestingly, the present results suggest that timemodulated metallic screens can be used either as pulsed sources (when ωs ω0) or as beamformers (when ωs ∼ ω0) to redirect energy in specific regions of space.

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Section: Introductionmentioning

confidence: 88%

Section: Theoretical Formalismmentioning

confidence: 99%

Section: F Time-varying Surface Current At the Discontinuity And Circ...mentioning

confidence: 99%

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Time-varying Metallic Interfaces

Alex‐Amor¹,

Molero²

2022

Preprint

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“…For instance, it is well known that graphene can act as a metal (good conductor) when it is electrically biased. Moreover, the sheet resistance of graphene can be reconfigured depending on the bias [46][47][48]. Thus, graphene can act as a good conductor (metal state), as a bad conductor, as an absorber, and as a transparent layer that is perfectly matched to the surrounding media [49,50].…”

Section: Introductionmentioning

confidence: 99%

Diffraction Phenomena in Time-Varying Metal-Based Metasurfaces

et al. 2023

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This paper presents an analytical framework for the analysis of time-varying metal-based metamaterials. Specifically, we particularize the study to time-modulated metal-air interfaces embedded between two different semi-infinite media that are illuminated by monochromatic plane waves of frequency ω 0 . The formulation is based on a Floquet-Bloch modal expansion, which takes into account the time periodicity of the structure (T s = 2π/ω s ) and integral-equation techniques. It allows us to extract the reflection and transmission coefficients as well as to derive nontrivial features about the dynamic response and dispersion curves of time-modulated metal-based screens. In addition, the proposed formulation has an associated analytical equivalent circuit that gives a physical insight into the diffraction phenomenon. Similarities and differences between space-and time-modulated metamaterials are discussed via the proposed circuit model. Finally, some analytical results are presented to validate the present framework. Good agreement is observed with numerical computations provided by a self-implemented finite-difference time-domain (FDTD) method. Interestingly, the present results suggest that time-modulated metal-based screens can be used as pulsed sources (when ω s ω 0 ), beam formers (ω s ∼ ω 0 ) to redirect energy in specific regions of space, and analog samplers (ω s ω 0 ).

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“…However, limitations in any of the carrier mobilities (electrons or holes), wider bandgaps and difficulties in their integration into silicon processes have limited the applications in complimentary MOS (CMOS) technology [6]. On the other hand, twodimensional materials, led by the discovery of graphene [9,10], have attracted tremendous attention due to their promising electrical properties [5,11]. Thanks to their low dimensionality, these thin materials present an optimal electrostatic control of the channel [12], flexibility and extremely sensitive capabilities to the changes in their surroundings.…”

Section: Introductionmentioning

confidence: 99%

Hysteresis in As-Synthesized MoS2 Transistors: Origin and Sensing Perspectives

et al. 2021

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Two-dimensional materials, including molybdenum disulfide (MoS2), present promising sensing and detecting capabilities thanks to their extreme sensitivity to changes in the environment. Their reduced thickness also facilitates the electrostatic control of the channel and opens the door to flexible electronic applications. However, these materials still exhibit integration difficulties with complementary-MOS standardized processes and methods. The device reliability is compromised by gate insulator selection and the quality of the metal/semiconductor and semiconductor/insulator interfaces. Despite some improvements regarding mobility, hysteresis and Schottky barriers having been reported thanks to metal engineering, vertically stacked heterostructures with compatible thin-layers (such as hexagonal boron nitride or device encapsulation) variability is still an important constraint to sensor performance. In this work, we fabricated and extensively characterized the reliability of as-synthesized back-gated MoS2 transistors. Under atmospheric and room-temperature conditions, these devices present a wide electrical hysteresis (up to 5 volts) in their transfer characteristics. However, their performance is highly influenced by the temperature, light and pressure conditions. The singular signature in the time response of the devices points to adsorbates and contaminants inducing mobile charges and trapping/detrapping carrier phenomena as the mechanisms responsible for time-dependent current degradation. Far from being only a reliability issue, we demonstrated a method to exploit this device response to perform light, temperature and/or pressure sensors in as-synthesized devices. Two orders of magnitude drain current level differences were demonstrated by comparing device operation under light and dark conditions while a factor up to 105 is observed at vacuum versus atmospheric pressure environments.

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Synthesis of graphene and other two-dimensional materials

Cited by 5 publications

References 508 publications

Time-varying Metallic Interfaces

Time-varying Metallic Interfaces

Diffraction Phenomena in Time-Varying Metal-Based Metasurfaces

Hysteresis in As-Synthesized MoS2 Transistors: Origin and Sensing Perspectives

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