Paving the Way for Tunable Graphene Plasmonic THz Amplifiers

This study reviews recent advances in room-temperature coherent amplification of terahertz (THz) radiation in graphene, electrically driven by a dry cell battery. Our study explores THz light–plasmon coupling, light absorption, and amplification using a current-driven graphene-based system because of its excellent room temperature electrical and optical properties. An efficient method to exploit graphene Dirac plasmons (GDPs) for light generation and amplification is introduced. This approach is based on current-driven excitation of the GDPs in a dual-grating-gate high-mobility graphene channel field-effect transistor (DGG-GFET) structure. The temporal response of the DGG-GFETs to the polarization-managed incident THz pulsation is experimentally observed by using THz time-domain spectroscopy. Their Fourier spectra of the transmitted temporal waveform through the GDPs reveals the device functions 1) resonant absorption at low drain bias voltages below the first threshold level, 2) perfect transparency between the first and the second threshold drain bias levels, and 3) resonant amplification beyond the second threshold drain bias voltage. The maximal gain of 9% is obtained by a monolayer graphene at room temperatures, which is four times higher than the quantum limit that is given when THz photons directly interact with electrons. The results pave the way toward tunable graphene plasmonic THz amplifiers.

Download Full-text

Photothermal, Photoelectric, and Photothermoelectric Effects in Bi-Sb Thin Films in the Terahertz Frequency Range at Room Temperature

Photonics ◽

10.3390/photonics8030076 ◽

2021 ◽

Vol 8 (3) ◽

pp. 76

Author(s):

Mikhail K. Khodzitsky ◽

Petr S. Demchenko ◽

Dmitry V. Zykov ◽

Anton D. Zaitsev ◽

Elena S. Makarova ◽

...

Keyword(s):

Thin Films ◽

Terahertz Radiation ◽

Room Temperature ◽

Voltage Drop ◽

Radiation Detection ◽

Radiation Detectors ◽

Thz Radiation ◽

Terahertz Frequency ◽

Frequency Range ◽

Terahertz Frequency Range

The terahertz frequency range is promising for solving various practically important problems. However, for the terahertz technology development, there is still a problem with the lack of affordable and effective terahertz devices. One of the main tasks is to search for new materials with high sensitivity to terahertz radiation at room temperature. Bi1−xSbx thin films with various Sb concentrations seem to be suitable for such conditions. In this paper, the terahertz radiation influence onto the properties of thermoelectric Bi1−xSbx 200 nm films was investigated for the first time. The films were obtained by means of thermal evaporation in vacuum. They were affected by terahertz radiation at the frequency of 0.14 terahertz (THz) in the presence of thermal gradient, electric field or without these influences. The temporal dependencies of photoconductivity, temperature difference and voltage drop were measured. The obtained data demonstrate the possibility for practical use of Bi1−xSbx thin films for THz radiation detection. The results of our work promote the usage of these thermoelectric materials, as well as THz radiation detectors based on them, in various areas of modern THz photonics.

Download Full-text

Fabrication of Graphene Nanomesh FET Terahertz Detector

Micromachines ◽

10.3390/mi12060641 ◽

2021 ◽

Vol 12 (6) ◽

pp. 641

Author(s):

Yuan Zhai ◽

Yi Xiang ◽

Weiqing Yuan ◽

Gang Chen ◽

Jinliang Shi ◽

...

Keyword(s):

Room Temperature ◽

Energy Gap ◽

Coupling Efficiency ◽

High Sensitivity ◽

Fabrication Process ◽

Monolayer Graphene ◽

Terahertz Waves ◽

Wet Process ◽

Graphene Nanomesh ◽

Thz Detector

High sensitivity detection of terahertz waves can be achieved with a graphene nanomesh as grating to improve the coupling efficiency of the incident terahertz waves and using a graphene nanostructure energy gap to enhance the excitation of plasmon. Herein, the fabrication process of the FET THz detector based on the rectangular GNM (r-GNM) is designed, and the THz detector is developed, including the CVD growth and the wet-process transfer of high quality monolayer graphene films, preparation of r-GNM by electron-beam lithography and oxygen plasma etching, and the fabrication of the gate electrodes on the Si3N4 dielectric layer. The problem that the conductive metal is easy to peel off during the fabrication process of the GNM THz device is mainly discussed. The photoelectric performance of the detector was tested at room temperature. The experimental results show that the sensitivity of the detector is 2.5 A/W (@ 3 THz) at room temperature.

Download Full-text

Local Structure and Er3+ Emission from Pseudo-Amorphous GaN:Er Thin Films

MRS Proceedings ◽

10.1557/proc-536-81 ◽

1998 ◽

Vol 536 ◽

Author(s):

S. B. Aldabergenova ◽

M. Albrecht ◽

A. A. Andreev ◽

C. Inglefield ◽

J. Viner ◽

...

Keyword(s):

Thin Films ◽

Room Temperature ◽

Amorphous Matrix ◽

Broad Band ◽

Resonant Absorption ◽

Absorption Bands ◽

Host Matrix ◽

Transmission Electron ◽

Infra Red ◽

Band Edge Luminescence

AbstractWe report on strong Er3+ luminescence in the visible and infra-red regions at room temperature in amorphous GaN:Er thin films prepared by DC magnetron co-sputtering. The intensity of the Er3+ luminescence at 1.535 μm corresponding to 4I13/2 → 4I15/2 transitions is greatly enhanced after annealing at 750°C. In this material GaN crystallites have formed and embedded in the continuous amorphous matrix. The crystallites are 4 to 7 nm in diameter as analyzed by high resolution transmission electron microscopy. The absorption edge, extending three orders of magnitude in absorption coefficient in the spectral range from 0.5 to 3.5 eV, is superimposed on resonant absorption bands of Er3+ ions.The total photoluminescence spectrum consists of welldefined Er3+ luminescence peaks imposed on a broad band edge luminescence from the amorphous GaN host matrix.

Download Full-text

THz technology for vision systems

Facta universitatis - series Electronics and Energetics ◽

10.2298/fuee1401129t ◽

2014 ◽

Vol 27 (1) ◽

pp. 129-136 ◽

Cited By ~ 1

Author(s):

J. Trontelj ◽

A. Sesek ◽

A. Svigelj

Keyword(s):

Room Temperature ◽

New Technology ◽

Electrical Engineering ◽

Thz Radiation ◽

Vision Systems ◽

Current Application ◽

Operating Range ◽

Imaging Results ◽

System Solution ◽

Thz Sensor

d.o.o, Sempeter pri Gorici, Slovenija KW nema KR nema The THz radiation brings new technology challenges and new opportunities to overcome some of the current application obstacles. In the paper a portable THz system is presented operating at room temperature. The presented solution is robust and inexpensive, convenient for many applications. The THz sensor fabricated at the Faculty of Electrical Engineering in the Laboratory for Microelectronics is currently one of the best sensors in its frequency operating range. It reaches sensitivity up to 1000V/W and NEP down to 5pW/?Hz in vacuum. With the proposed system solution variety of application can be covered. Some imaging results captured with the proposed system at different stand-off distances are shown in the paper.

Download Full-text

Polarization-Insensitive Dielectric Metamaterials Absorber for Near-Unity UV-Light Trapping in Monolayer Graphene

10.21203/rs.3.rs-117470/v1 ◽

2020 ◽

Author(s):

Yinong Xie ◽

Xueying Liu ◽

Yijun Cai ◽

Jinfeng Zhu

Keyword(s):

Magnetic Resonance ◽

High Performance ◽

Uv Light ◽

Light Trapping ◽

Normal Incidence ◽

Resonant Absorption ◽

Base Layer ◽

Absorption Enhancement ◽

Monolayer Graphene ◽

Polarization Insensitive

Abstract With the aim of improving UV light trapping capability in monolayer graphene, a metamaterials absorber is proposed, which exhibits the polarization-insensitive feature due to the geometrical symmetry. Through the functional combination of magnetic resonance and UV mirror, the absorption of unpolarized UV light in monolayer graphene can reach 99.5% under normal incidence. The absorption enhancement is induced by the magnetic resonance mode between the dielectric silica nanomesh and the calcium fluoride base layer. The effects of geometric parameters on the absorption spectra are systematically investigated. By optimizing the metamaterials design, two distinct resonant absorption peaks can be excited simultaneously for monolayer graphene. Our work paves the way for applications on high-performance UV metamaterials devices by using two-dimensional materials.

Download Full-text

Investigations on non-classical silylium ions leading to a cyclobutenyl cation

Chemical Science ◽

10.1039/c8sc04591g ◽

2019 ◽

Vol 10 (9) ◽

pp. 2821-2829 ◽

Cited By ~ 6

Author(s):

Arthur Martens ◽

Marvin Kreuzer ◽

Alexander Ripp ◽

Marius Schneider ◽

Daniel Himmel ◽

...

Keyword(s):

Dft Calculations ◽

Room Temperature ◽

The Way

The formation of simple non-classical silylium ions from [Me3Si]+ sources and alkenes or alkynes was investigated, but mainly oligomerization was observed. Yet, the reaction with MeCCMe led to a room temperature stable cyclobutenyl cation. DFT calculations suggest that a non-classical silylium ion intermediate was formed on the way to this product.

Download Full-text

High mobility amorphous/nanocrystalline indium zinc oxide deposited at room temperature

Thin Solid Films ◽

10.1016/j.tsf.2005.07.311 ◽

2006 ◽

Vol 502 (1-2) ◽

pp. 104-107 ◽

Cited By ~ 62

Author(s):

E. Fortunato ◽

A. Pimentel ◽

A. Gonçalves ◽

A. Marques ◽

R. Martins

Keyword(s):

Zinc Oxide ◽

Room Temperature ◽

High Mobility ◽

Indium Zinc Oxide

Download Full-text

High Mobility a-IGO Films Produced at Room Temperature and Their Application in TFTs

Electrochemical and Solid-State Letters ◽

10.1149/1.3257613 ◽

2010 ◽

Vol 13 (1) ◽

pp. H20 ◽

Cited By ~ 36

Author(s):

G. Gonçalves ◽

P. Barquinha ◽

L. Pereira ◽

N. Franco ◽

E. Alves ◽

...

Keyword(s):

Room Temperature ◽

High Mobility

Download Full-text

TRAP BEHAVIOR IN AlGaN/GaN HEMTs BY POST-GATE-ANNEALING

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156404002818 ◽

2004 ◽

Vol 14 (03) ◽

pp. 769-774

Author(s):

HYEONGNAM KIM ◽

JAESUN LEE ◽

WU LU

Keyword(s):

Time Constant ◽

High Mobility ◽

Time Constants ◽

Emission Time ◽

Annealing Effects ◽

Drain Bias ◽

Gan Hemts ◽

Electron Transistors ◽

Shallow Traps ◽

Transient Measurements

Trapping effects are investigated to examine the post-gate annealing effects on AlGaN/GaN high-mobility electron transistors (HEMTs) using pulsed I-V and transient measurements. In the unannealed devices, shallow traps are identified, which have an activation of 38 meV at a drain bias of 7 V. The time constant of these traps is determined to be ~0.5 μs. Devices annealed at 400°C for 10 minutes have a significantly smaller number of traps. However, a small number of traps with a longer time constant of 9.2 μs are created or activated during post-gate annealing. 20-minute annealing at 400°C leads to the increase of the number of traps with emission time constants of 21.6 μs and 1.25 ms. The breakdown voltage improvement by post-gate annealing is attributed to the removal or significant reduction of the shallow level traps.

Download Full-text