Structure-selected graphene/metallic surface plasmon coupling regime and infrared modulation application

2021 ◽  
Author(s):  
Ye Zhang ◽  
Jianjun Lai ◽  
Changhong Chen
Keyword(s):  
Gate Dielectric ◽  
Modulation Depth ◽  
Strong Dependence ◽  
Underlying Mechanism ◽  
Absorption Enhancement ◽  
Metallic Surface ◽  
Dielectric Thickness ◽  
Long Wavelength ◽  
Surface Plasmon Coupling ◽  
Induced Transparency

Abstract Here we present a graphene-based long-wavelength infrared modulator characteristic of extra-high contrast, where the frequency detuning degree of magnetic and electric surface plasmons (SPs) is controllable by the gated graphene Fermi energy. If the device is designed to work in a strong SP-coupling regime by selecting an appropriate low-lossy gate dielectric thickness, a modulation depth (MD) up to ~100% but insertion loss (IL) as low as ~-0.37 dB is achievable. Moreover, a compromised MD >90% with IL <-1.0 dB is still retainable in two broadband ranges. The disclosed underlying mechanism to the device working state in the strong, electromagnetic-induced transparency (EIT), or weak SP-coupling regime, indicates the coupling regime shows a strong dependence on the dielectric thickness, which is related to the magnetic-SP mode volume, while the working wavelength can be selected in a broader spectral range by scaling the device geometry. These findings are helpful to construct those optoelectronics for infrared absorption enhancement, EIT, and strong coupling spectral characteristic itself.

Enhanced Optical Absorption of Dual-Diameter Structured Silicon Nanoholes Array

2020 ◽  
Vol 976 ◽  
pp. 116-120
Author(s):  
Yi Liu ◽  
Na Meng ◽  
Ya Wei Kuang ◽  
Shu Chang Wang ◽  
Zhi Chun Ni ◽  
...  
Keyword(s):  
Crystalline Silicon ◽  
Structural Parameters ◽  
Underlying Mechanism ◽  
Absorption Enhancement ◽  
Optimal Parameters ◽  
Silicon Thin Film ◽  
Long Wavelength ◽  
Enhancement Factors ◽  
Wavelength Absorption ◽  
Wavelength Control

The optical properties have been numerically investigated in crystalline silicon nanoholes array for various structural parameters. We have demonstrated that the light absorption can be greatly enhanced in silicon nanoholes array especially for long wavelength absorption compared with single diameter nanoholes array. We have also obtained the optimal parameters for absorption wavelength control, at which the photocurrent enhancement factors have been achieved to be 14.43% compared to silicon thin film. Furthermore, the underlying mechanism of the absorption enhancement in dual-diameter nanoholes array has been discussed.

Dynamically tunable plasmon-induced transparency effect based on graphene metasurfaces

2021 ◽  
Author(s):  
Shuxian Chen ◽  
Junyi Li ◽  
Zicong Guo ◽  
Li Chen ◽  
Kunhua Wen ◽  
...  
Keyword(s):  
Modulation Depth ◽  
Incident Light ◽  
Polarization Angle ◽  
Refractive Index Sensitivity ◽  
Coupled Mode ◽  
Terahertz Devices ◽  
Index Sensitivity ◽  
Induced Transparency ◽  
Difference Time ◽  
Plasmon Induced Transparency

Abstract Plasmon-induced transparency (PIT) is theoretically explored with a graphene metamaterial using finite-difference time-domain numerical simulations and coupled-mode-theory theoretical analysis. In this work, the proposed structure is consisted of one rectangular cavity and three strips to generate the PIT phenomenon. The PIT window can be regulated dynamically by adjusting the Fermi level of the graphene. Importantly, the modulation depth of the amplitude can reach 90.4%. The refractive index sensitivity of the PIT window is also investigated, and the simulation result shows that a sensitivity of 1.335 THz/RIU is achieved. Additionally, when the polarization angle of the incident light is changed gradually from 0˚ to 90˚, the performances of the structure are greatly affected. Finally, the proposed structure is particularly enlightening for the design of dynamically tuned terahertz devices.

Light Trapping in Thin Film Silicon n-i-p Solar Cells - Gains and Losses

2008 ◽  
Vol 1101 ◽  
Author(s):  
Ruud E.I. Schropp ◽  
Hongbo Li ◽  
Jatin K. Rath ◽  
Ronald H. Franken
Keyword(s):  
Thin Film ◽  
Light Trapping ◽  
Structural Defects ◽  
Metallic Surface ◽  
Textured Surfaces ◽  
Long Wavelength ◽  
Thin Film Silicon ◽  
Internal Surfaces ◽  
Gains And Losses ◽  
Wavelength Light

AbstractThin film silicon solar cell technology frequently makes use of rough or textured surfaces in order to enhance light absorption within the thin absorber layers by scattering and total internal reflection (“light trapping”). The rough morphology of the optically functional internal surfaces both in superstrate and substrate cells however, not only has a beneficial effect on light scattering properties, but on the other hand may also have deleterious effects on the microscopic structure of the deposited layers, in particular if these layers are nanocrystalline. The narrow valleys in the surface morphology may lead to structural defects, such as cavities and pinholes. By adjusting the morphology, these defects can be avoided.However, even when structural defects in layers directly deposited on rough interfaces are avoided, the obtained optically defined maximum current density is still much lower than expected. For instance, in n-i-p structures the rough interface (the textured back reflector consisting of nanostructured Ag coated with ZnO) is located at the back of the cell, where only long wavelength light is present. The natively textured Ag film is sputtered at elevated temperature and optimized for diffusely reflecting this long wavelength light. From experiments we infer that the nanostructured metallic surface also gives rise to plasmon absorption in the red and near IR, and that this leads to a parasitic absorption, i.e. at least part of the absorbed energy is not re-emitted to the active layers.

Stability of strong electromagnetic waves in overdense plasmas against long-wavelength perturbations

1985 ◽  
Vol 33 (2) ◽  
pp. 285-301 ◽  
Author(s):  
F. J. Romeiras ◽  
G. Rowlands
Keyword(s):  
Dispersion Relation ◽  
Nonlinear Waves ◽  
Electromagnetic Waves ◽  
Modulation Depth ◽  
Longitudinal Direction ◽  
Transverse Component ◽  
Ion Density ◽  
Long Wavelength ◽  
The Stability ◽  
Two Parameters

We consider the stability against long-wavelength small parallel perturbations of a class of exact standing wave solutions of the equations that describe an unmagnetized relativistic overdense cold electron plasma. The main feature of these nonlinear waves is a circularly polarized transverse component of the electric field periodically modulated in the longitudinal direction. Using an analytical method developed by Rowlands we obtain a dispersion relation valid for long-wavelength perturbations. This dispersion relation is a biquadratic equation in the phase velocity of the perturbations whose coefficients are very complicated functions of the two parameters used to define the nonlinear waves: the normalized ion density and a quantity related to the modulation depth. This dispersion relation is discussed for the whole range of the two parameters revealing, in particular, the existence of a region in parameter space where the nonlinear waves are stable.

Impact of gate dielectric thickness on the electrical properties of AlGaN/GaN MISHFETs on Si(111) substrate

2010 ◽  
Vol 207 (6) ◽  
pp. 1342-1344 ◽  
Author(s):  
Martin Eickelkamp ◽  
Dirk Fahle ◽  
Johannes Lindner ◽  
Michael Heuken ◽  
Christian Lautensack ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Gate Dielectric ◽  
Dielectric Thickness

Engineered Absorption Enhancement and Induced Transparency in Coupled Molecular and Plasmonic Resonator Systems

Nano Letters ◽  
2013 ◽  
Vol 13 (6) ◽  
pp. 2584-2591 ◽  
Author(s):  
Ronen Adato ◽  
Alp Artar ◽  
Shyamsunder Erramilli ◽  
Hatice Altug
Keyword(s):  
Absorption Enhancement ◽  
Induced Transparency ◽  
Plasmonic Resonator

Modeling and Designing a Device Using MuGFETs

2008 ◽  
Author(s):  
V. K. Lamba ◽  
Derick Engles ◽  
S. S. Malik
Keyword(s):  
Gate Dielectric ◽  
Silicon Film ◽  
General Rule ◽  
Channel Length ◽  
Silicon On Insulator ◽  
Oxide Semiconductor ◽  
Radius Of Curvature ◽  
Short Channel ◽  
Dielectric Thickness ◽  
Fin Thickness

This work describes computer simulations of various, Silicon on Insulator (SOI) Metal Oxide Semiconductor Field Effect Transistor (MOSFETs) with double and triple-gate structures, as well as gate-all-around devices. To explore the optimum design space for four different gate structures, simulations were performed with four variable device parameters: gate length, channel width, doping concentration, and silicon film thickness. The efficiency of the different gate structures is shown to be dependent of these parameters. Here short-channel properties of multi-gate SOI MOSFETs (MuGFETs) are studied by numerical simulation. The evolution of characteristics such as Drain induced barrier lowering (DIBL), sub-threshold slope, and threshold voltage roll-off is analyzed as a function of channel length, silicon film or fin thickness, gate dielectric thickness and dielectric constant, and as a function of the radius of curvature of the corners. The notion of an equivalent gate number is introduced. As a general rule, increasing the equivalent gate number improves the short-channel behavior of the devices. Similarly, increasing the radius of curvature of the corners improves the control of the channel region by the gate.

Effects of PECVD SiO₂ Gate Dielectric Thickness on Recessed AlGaN/GaN MOS-HFETs

2018 ◽  
Vol 18 (2) ◽  
pp. 187-192 ◽  
Author(s):  
Hyun-Seop Kim ◽  
Won-Ho Jang ◽  
Su-Keun Eom ◽  
Sang-Woo Han ◽  
Hyungtak Kim ◽  
...  
Keyword(s):  
Gate Dielectric ◽  
Dielectric Thickness

scholarly journals Light Absorption Enhancement in Organic Solar Cell by Embedding Ag Nanoparticles and Nanochains within the Active Layer

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sheng-Qing Zhu ◽  
Tong Zhang ◽  
Xin-Li Guo ◽  
Feng Shan ◽  
Xiao-Yang Zhang
Keyword(s):  
Active Layer ◽  
Light Absorption ◽  
Ag Nanoparticles ◽  
Organic Solar Cell ◽  
Organic Photovoltaic ◽  
Localized Surface Plasmon ◽  
Absorption Enhancement ◽  
Long Wavelength ◽  
Monodisperse Nanoparticles ◽  
Different Types

We numerically investigate the light absorption enhancement of organic photovoltaic cells by embedding Ag nanoparticles and nanochains within the active layer using a finite element method. We analyze the enhancement mechanism of light absorption and systematically study the influence of factors such as the size and the period of silver nanoparticles. The result shows the localized surface plasmon resonance of the particles has a significant influence on the light absorption. Under AM1.5 illumination condition, a relative enhancement with a factor of 107.1% is observed for nanoparticles with a diameter of 30 nm and a period of 200 nm. In addition, different types of nanochain structures have been studied, and we find that, comparing to monodisperse nanoparticles, nanochain structures can further enhance the light absorption because of the stronger light harvesting in the long wavelength range of 600–800 nm.

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