Терагерцовые дисперсия и усиление при стриминге электронов в графене при 300 K

Abstract We interpret the recent observations of Otsuji’s team (Sendai) on switching from absorption to amplification at a temperature of T = 300 K during the passage of terahertz radiation through hexagonal boron nitride–graphene sandwiches with multiple gates on the surface with an increase in the electric field in graphene. It is shown that these effects are related to dispersion and negative conductivity near the transit-time frequency of electrons in momentum space under streaming (anisotropic distribution) in graphene in a strong electric field. On the basis of these data, a universal tunable terahertz source is proposed, which has the form of a graphene-containing sandwich with a high-resistance silicon wafer (a cavity) with an applied voltage. This terahertz cavity is a complete analog of the microwave generator implemented on an InP chip by Vorobev’s team (St. Petersburg).

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The controllable tuning of nanofriction on atomically thin hexagonal boron nitride with external electric field

Applied Surface Science ◽

10.1016/j.apsusc.2021.152361 ◽

2021 ◽

pp. 152361

Author(s):

Xingyuan Chen ◽

Yao Huang ◽

Kun Zou ◽

Yitian Peng

Keyword(s):

Boron Nitride ◽

Electric Field ◽

External Electric Field ◽

Hexagonal Boron Nitride

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Tuning Electronic and Structural Properties of Triple Layers of Intercalated Graphene and Hexagonal Boron Nitride: An Ab-initio Study.

MRS Proceedings ◽

10.1557/opl.2011.364 ◽

2011 ◽

Vol 1307 ◽

Author(s):

Samir S. Coutinho ◽

David L. Azevedo ◽

Douglas S. Galvão

Keyword(s):

Boron Nitride ◽

Electric Field ◽

Ab Initio ◽

Band Gap ◽

External Electric Field ◽

Structural Properties ◽

Density Functional ◽

Hexagonal Boron Nitride ◽

Electronic And Structural Properties ◽

Gap Values

ABSTRACTRecently, several experiments and theoretical studies demonstrated the possibility of tuning or modulating band gap values of nanostructures composed of bi-layer graphene, bi-layer hexagonal boron-nitride (BN) and hetero-layer combinations. These triple layers systems present several possibilities of stacking. In this work we report an ab initio (within the formalism of density functional theory (DFT)) study of structural and electronic properties of some of these stacked configurations. We observe that an applied external electric field can alter the electronic and structural properties of these systems. With the same value of the applied electric field the band gap values can be increased or decreased, depending on the layer stacking sequences. Strong geometrical deformations were observed. These results show that the application of an external electric field perpendicular to the stacked layers can effectively be used to modulate their inter-layer distances and/or their band gap values.

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Investigation of switching uniformity in resistive memory via finite element simulation of conductive-filament formation

Scientific Reports ◽

10.1038/s41598-021-81896-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kyunghwan Min ◽

Dongmyung Jung ◽

Yongwoo Kwon

Keyword(s):

Finite Element ◽

Electric Field ◽

High Resistance ◽

Applied Voltage ◽

Vacancy Concentration ◽

Anion Vacancy ◽

Phase Variable ◽

Filament Formation ◽

Conductive Filament ◽

Switching Material

AbstractHerein, we present simulations of conductive filament formation in resistive random-access memory using a finite element solver. We consider the switching material, which is typically an oxide, as a two-phase material comprising low- and high-resistance phases. The low-resistance phase corresponds to a defective and conducting region with a high anion vacancy concentration, whereas the high-resistance phase corresponds to a non-defective and insulating region with a low anion-vacancy concentration. We adopt a phase variable corresponding to 0 and 1 in the insulating and conducting phases, respectively, and we change the phase variable suitably when new defects are introduced during voltage ramp-up for forming. Initially, some defects are embedded in the switching material. When the applied voltage is ramped up, the phase variable changes from 0 to 1 at locations wherein the electric field exceeds a critical value, which corresponds to the introduction of new defects via vacancy generation. The applied voltage at which the defects percolate to form a filament is considered as the forming voltage. Here, we study the forming-voltage uniformity using simulations, and we find that for typical planar-electrode devices, the forming voltage varies significantly owing to the stochastic location of the initial defects at which the electric field is “crowded.” On the other hand, a protruding electrode can improve the switching uniformity drastically via facilitating the deterministic location of electric-field crowding, which also supported by the reported experimental results.

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Photovoltage Oscillations in Encapsulated Graphene

10.21203/rs.3.rs-1241571/v1 ◽

2022 ◽

Author(s):

Jesús Iñarrea ◽

Gloria Platero

Keyword(s):

Boron Nitride ◽

Terahertz Radiation ◽

Gate Voltage ◽

Hexagonal Boron Nitride ◽

Monolayer Graphene ◽

Dirac Fermions ◽

Positive Voltage ◽

Carrier Effective Mass ◽

Electron Orbit ◽

Orbit Model

Abstract We theoretically analyze the rise of photovoltage oscillations in hexagonal boron-nitride (h-BN) encapsulated monolayer graphene (h-BN/graphene/h-BN) when irradiated with terahertz radiation. We use an extension of the radiation-driven electron orbit model, successfully applied to study the oscillations obtained in irradiated magnetotransport of GaAs/AlGaAs heterostructures. The extension takes mainly into account that now the carriers are massive Dirac fermions. Our simulations reveal that the photovoltage in these graphene systems presents important oscillations similar to the ones of irradiated magnetoresistance in semiconductor platforms but in the terahertz range. We also obtain that these oscillations are clearly affected by the voltages applied to the sandwiched graphene: a vertical gate voltage between the two hBN layers and an external positive voltage applied to one of the sample sides. The former steers the carrier effective mass and the latter the photovoltage intensity and the oscillations amplitude. The frequency dependence of the photo-oscillations is also investigated.

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Influence of Electric Field on the Mechanical Properties of Hexagonal Boron-Nitride Sheets Using ab-initio Calculations

NANO ◽

10.1142/s1793292015500472 ◽

2015 ◽

Vol 10 (03) ◽

pp. 1550047 ◽

Cited By ~ 6

Author(s):

R. Ansari ◽

S. Malakpour ◽

M. Faghihnasiri ◽

S. Ajori

Keyword(s):

Mechanical Properties ◽

Boron Nitride ◽

Electric Field ◽

Density Functional ◽

Hexagonal Boron Nitride ◽

High Sensitivity ◽

Functional Theory ◽

Zigzag Direction ◽

Electric Filed ◽

Armchair Direction

In some cases such as assembling nanodevices and nanobiosensing, the effect of electric filed on the mechanical properties of nanomaterials is important and should be taken into account. The aim of this work is to investigate the effect of electric field on the mechanical properties of hexagonal boron-nitride (h-BN) using density functional theory (DFT) calculations. The results show the high sensitivity of mechanical properties to the magnitude and direction of electric field. It is observed that imposing the electric field on the armchair direction, unlike the zigzag direction, increases the magnitude of elastic properties of h-BN especially in the case of Poisson's ratio. It is further observed that the electric field perpendicular to h-BN has a negligible effect on its mechanical properties.

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Unipolar Switching Behavior in Highly Crystalline Hexagonal Boron Nitride

MRS Proceedings ◽

10.1557/opl.2014.503 ◽

2014 ◽

Vol 1658 ◽

Cited By ~ 1

Author(s):

Nikhil Jain ◽

Robin B. Jacobs-Gedrim ◽

Bin Yu

Keyword(s):

Boron Nitride ◽

Electric Field ◽

Hexagonal Boron Nitride ◽

Electrical Characterization ◽

Information Storage ◽

Switching Behavior ◽

Reconfigurable Logic ◽

Substitutional Doping ◽

Capacitance Voltage

ABSTRACTWe observed resistive switching in highly crystalline layered insulator hexagonal boron nitride (h-BN) under electric field in a nano-device configuration. Two distinct resistive states were observed in the 2D material heterostack. Electrical characterization using capacitance-voltage approach further revealed the role of h-BN as the active switching element. The switching behavior could be attributed to substitutional doping of h-BN under electric field present in the active region, possibly resulting in the formation of multi-element complex in which electrical conductivity depends on the amount of substituted dopant in the boron nitride crystal lattice. Since switching is observed independent of the direction of electric field, it is unipolar in nature. The observed memristance phenomenon in layered insulator may be potentially used in the form of NVM, providing possible direction to implement information storage or reconfigurable logic applications.

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