Plasmon modes in graphene — GaAs heterostructures at finite temperature

2019 ◽  
Vol 33 (16) ◽  
pp. 1950174 ◽  
Author(s):  
Nguyen Van Men ◽  
Dong Thi Kim Phuong
Keyword(s):  
Quantum Well ◽  
Finite Temperature ◽  
Random Phase ◽  
Monolayer Graphene ◽  
Layer System ◽  
Exchange Correlation ◽  
Plasmon Frequency ◽  
Quantum Well Width ◽  
Double Layer System ◽  
Plasmon Modes

This paper is to investigate the dispersion relation and decay rate of plasmon modes in a double layer system made of monolayer graphene (MLG) and infinite GaAs quantum well at finite temperature within the generalized random-phase-approximation and taking into account the 2DEG layer-thickness and the inhomogeneity of the background dielectric. Calculations demonstrate that when the quantum well width increases, the acoustic (AC) plasmon frequency decreases dramatically, but the optical (OP) one seems unchanged. In addition, the results also illustrate that the temperature and separated distance affect significantly both AC and OP plasmon modes of the system. Finally, the dielectric of the background acts strongly on the OP plasmon curve while carrier density in two layers and exchange-correlation effects only lead to remarkable changes for the acoustic one.

Plasmon modes in bilayer-graphene–GaAs heterostructures including layer-thickness and exchange-correlation effects

2018 ◽  
Vol 32 (23) ◽  
pp. 1850256 ◽  
Author(s):  
Nguyen Van Men ◽  
Dong Thi Kim Phuong
Keyword(s):  
Quantum Well ◽  
Layer Thickness ◽  
Random Phase ◽  
Bilayer Graphene ◽  
Monolayer Graphene ◽  
Layer System ◽  
Exchange Correlation ◽  
Quantum Well Width ◽  
Double Layer System ◽  
Plasmon Modes

We investigate the dispersion relation and decay rate of plasmon modes in a double-layer system made of bilayer graphene (BLG) and infinite GaAs quantum well at zero-temperature within the generalized random-phase-approximation and taking into account the 2DEG layer-thickness and inhomogeneity of the background dielectric. We illustrate that the acoustic plasmon dispersion curve of the considered system differs significantly from that of monolayer graphene (MLG)–GaAs heterostructure and BLG–GaAs without layer-thickness. Calculations also demonstrate that meanwhile the optical plasmon curve is affected slightly by spacer width and exchange-correlation, the acoustic one depends remarkably on the interlayer distance, inhomogeneity of the background dielectric, carrier densities, spacer dielectric constant, quantum well width and exchange-correlations.

scholarly journals Plasmon modes in Dirac–Schrödinger hybrid electron systems including layer-thickness and exchange-correlation effects

2018 ◽  
Vol 96 (6) ◽  
pp. 615-621 ◽  
Author(s):  
Nguyen Van Men ◽  
Nguyen Quoc Khanh
Keyword(s):  
Layer Thickness ◽  
Random Phase ◽  
Dielectric Constants ◽  
Monolayer Graphene ◽  
Correlation Effects ◽  
Layer System ◽  
Optical Branch ◽  
Exchange Correlation ◽  
Damping Rate ◽  
Double Layer System

We calculate the plasmon dispersion relation and damping rate of collective excitations in a double-layer system consisting of monolayer graphene and GaAs quantum well at zero temperature including layer-thickness and exchange-correlation effects. We use the generalized random-phase-approximation dielectric function and take into account the nonhomogeneity of the dielectric background of the system. We show that the effects of layer thickness, electron densities, and exchange-correlations are more pronounced for acoustic modes, while the optical branch depends remarkably on dielectric constants of the contacting media.

scholarly journals The scattering time of electrons in a GaAs/InGaAs/GaAs quantum well including temperature and exchange-correlation effects

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Truong Van Tuan ◽  
Nguyen Quoc Khanh ◽  
Vo Van Tai
Keyword(s):  
Surface Roughness ◽  
Relaxation Time ◽  
Quantum Well ◽  
Impurity Scattering ◽  
Correlation Effects ◽  
Charged Impurity ◽  
Exchange Correlation ◽  
Local Field Correction ◽  
Quantum Well Width ◽  
Charged Impurity Scattering

The ratio of the scattering and single-particle relaxation time of a quasi-two-dimensional electron gas (Q2DEG) in a finite lattice-mismatched GaAs/InGaAs/GaAs quantum well was investigate at zero and finite temperatures, taking into account the exchange-correlation effects via a local-field correction with three approximations for the LFC, G = 0, GH, and GGA. We studied the dependence of the surface roughness, roughness-induced piezoelectric, remote and homogenous background charged impurity scattering on the carrier density and quantum well width. In the case of zero temperature and Hubbard local-field correction our results reduced to those of different theoretical calculations. At low density, the exchange-correlation effects depend strongly on the ratio τt/τs. While at high density many-body effects due to exchange and correlation considerably modified the ratio of the scattering and single-particle relaxation time. We found that, for densities and temperatures considered T = 0,3TF in this study, the temperature affected weakly on the time ratio for four scatterings. Furthermore, with the change of quantum well width, the effect of LFC and temperatures act on the ratio τt/τs are negligible for the roughness-induced piezoelectric and remote charged impurity scattering, and are notable for the surface roughness and homogenous background charged impurity scattering.

EFFECTS OF DIELECTRIC MISMATCH ON THE PLASMONS IN QUANTUM WELL SYSTEMS

2003 ◽  
Vol 17 (31n32) ◽  
pp. 6073-6083
Author(s):  
XI-LI ZHANG ◽  
XUE-HUA WANG ◽  
XIN-HAI LIU ◽  
BEN-YUAN GU
Keyword(s):  
Quantum Well ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Field Method ◽  
Single Quantum Well ◽  
One Dimensional ◽  
Self Consistent Field ◽  
The One ◽  
Plasmon Modes ◽  
Dielectric Mismatch

In the framework of random-phase approximation theory and applying the self-consistent field method, we study the properties of collective charge density excitations in single quantum well in consideration of dielectric mismatch. We analytically give the general solution of the image potential to the one dimensional Green's function. Our numerical results demonstrate that the dielectric mismatch between the barrier and well materials significantly changes the frequency of the intra- and inter-subband plasmon modes in contrast with dielectric match. We reasonably conclude that the image potential affects the intra- and inter-subband plasmon modes in a different way.

scholarly journals Dimension control of in situ fabricated CsPbClBr2 nanocrystal films toward efficient blue light-emitting diodes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Chenhui Wang ◽  
Dengbao Han ◽  
Junhui Wang ◽  
Yingguo Yang ◽  
Xinyue Liu ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Blue Emission ◽  
Light Emitting ◽  
Mixed Ligands ◽  
Dimension Control ◽  
Nanocrystal Films ◽  
Width Distribution ◽  
Quantum Well Width

AbstractIn the field of perovskite light-emitting diodes (PeLEDs), the performance of blue emissive electroluminescence devices lags behind the other counterparts due to the lack of fabrication methodology. Herein, we demonstrate the in situ fabrication of CsPbClBr2 nanocrystal films by using mixed ligands of 2-phenylethanamine bromide (PEABr) and 3,3-diphenylpropylamine bromide (DPPABr). PEABr dominates the formation of quasi-two-dimensional perovskites with small-n domains, while DPPABr induces the formation of large-n domains. Strong blue emission at 470 nm with a photoluminescence quantum yield up to 60% was obtained by mixing the two ligands due to the formation of a narrower quantum-well width distribution. Based on such films, efficient blue PeLEDs with a maximum external quantum efficiency of 8.8% were achieved at 473 nm. Furthermore, we illustrate that the use of dual-ligand with respective tendency of forming small-n and large-n domains is a versatile strategy to achieve narrow quantum-well width distribution for photoluminescence enhancement.

Plasmon modes in N-layer silicene structures

2021 ◽  
Author(s):  
Men Nguyen Van
Keyword(s):  
Electric Field ◽  
Random Phase ◽  
Single Layer ◽  
Plasmon Mode ◽  
Orbit Coupling ◽  
Collective Excitations ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Number Of Layers ◽  
Plasmon Modes

Abstract We investigate the plasmon properties in N-layer silicene systems consisting of N, up to 6, parallel single-layer silicene under the application of an out-of-plane electric field, taking into account the spin-orbit coupling within the random-phase approximation. Numerical calculations demonstrate that N undamped plasmon modes, including one in-phase optical and (N-1) out-of-phase acoustic modes, continue mainly outside the single-particle excitation area of the system. As the number of layers increases, the frequencies of plasmonic collective excitations increase and can become much larger than that in single layer silicene, more significant for high-frequency modes. The optical (acoustic) plasmon mode(s) noticeably (slightly) decreases with the increase in the bandgap and weakly depends on the number of layers. We observe that the phase transition of the system weakly affects the plasmon properties, and as the bandgap caused by the spin-orbit coupling equal that caused by the external electric field, the plasmonic collective excitations and their broadening function in multilayer silicene behave similarly to those in multilayer gapless graphene structures. Our investigations show that plasmon curves in the system move toward that in single layer silicene as the separation increases, and the impacts of this factor can be raised by a large number of layers in the system. Finally, we find that the imbalanced carrier density between silicene layers significantly decreases plasmon frequencies, depending on the number of layers.

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