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https://www.readbyqxmd.com/read/28646225/a-high-power-broadband-terahertz-source-enabled-by-three-dimensional-light-confinement-in-a-plasmonic-nanocavity
#1
Nezih Tolga Yardimci, Semih Cakmakyapan, Soroosh Hemmati, Mona Jarrahi
The scope and potential uses of time-domain terahertz imaging and spectroscopy are mainly limited by the low optical-to-terahertz conversion efficiency of photoconductive terahertz sources. State-of-the-art photoconductive sources utilize short-carrier-lifetime semiconductors to recombine carriers that cannot contribute to efficient terahertz generation and cause additional thermal dissipation. Here, we present a novel photoconductive terahertz source that offers a significantly higher efficiency compared with terahertz sources fabricated on short-carrier-lifetime substrates...
June 23, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28644642/probing-electron-phonon-interaction-through-two-photon-interference-in-resonantly-driven-semiconductor-quantum-dots
#2
Antoine Reigue, Jake Iles-Smith, Fabian Lux, Léonard Monniello, Mathieu Bernard, Florent Margaillan, Aristide Lemaitre, Anthony Martinez, Dara P S McCutcheon, Jesper Mørk, Richard Hostein, Valia Voliotis
We investigate the temperature dependence of photon coherence properties through two-photon interference (TPI) measurements from a single quantum dot (QD) under resonant excitation. We show that the loss of indistinguishability is related only to the electron-phonon coupling and is not affected by spectral diffusion. Through these measurements and a complementary microscopic theory, we identify two independent separate decoherence processes, both of which are associated with phonons. Below 10 K, we find that the relaxation of the vibrational lattice is the dominant contribution to the loss of TPI visibility...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644637/comment-on-quasi-one-dimensional-metal-insulator-transitions-in-compound-semiconductor-surfaces
#3
Sun-Woo Kim, Yoon-Gu Kang, Hyun-Jung Kim, Jun-Hyung Cho
No abstract text is available yet for this article.
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644636/path-controlled-time-reordering-of-paired-photons-in-a-dressed-three-level-cascade
#4
Samir Bounouar, Max Strauß, Alexander Carmele, Peter Schnauber, Alexander Thoma, Manuel Gschrey, Jan-Hindrik Schulze, André Strittmatter, Sven Rodt, Andreas Knorr, Stephan Reitzenstein
The two-photon dressing of a "three-level ladder" system, here the ground state, the exciton, and the biexciton of a semiconductor quantum dot, leads to new eigenstates and allows one to manipulate the time ordering of the paired photons without unitary postprocessing. We show that, after spectral postselection of the single dressed states, the time ordering of the cascaded photons can be removed or conserved. Our joint experimental and theoretical study demonstrates the high potential of a "ladder" system to be a versatile source of orthogonally polarized, bunched or antibunched pairs of photons...
June 9, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28644493/photoelectrochemical-devices-for-solar-water-splitting-materials-and-challenges
#5
Chaoran Jiang, Savio J A Moniz, Aiqin Wang, Tao Zhang, Junwang Tang
It is widely accepted within the community that to achieve a sustainable society with an energy mix primarily based on solar energy we need an efficient strategy to convert and store sunlight into chemical fuels. A photoelectrochemical (PEC) device would therefore play a key role in offering the possibility of carbon-neutral solar fuel production through artificial photosynthesis. The past five years have seen a surge in the development of promising semiconductor materials. In addition, low-cost earth-abundant co-catalysts are ubiquitous in their employment in water splitting cells due to the sluggish kinetics of the oxygen evolution reaction (OER)...
June 23, 2017: Chemical Society Reviews
https://www.readbyqxmd.com/read/28644149/thermal-transport-in-monolayer-inse
#6
Arun Nissimagoudar, Jinlong Ma, Yani Chen, Wu Li
Two-dimensional InSe, a recently synthesized semiconductor having a moderate band gap, has gained attention due to its ultra high mobility and high photo-responsivity. In this work, we calculate the lattice thermal conductivity (κ) of monolayer InSe by solving the phonon Boltzmann transport equation (BTE) with first-principles calculated inter atomic force constants. κ of monolayer InSe is isotropic and found to be around 27.6 W/m-K at room temperature along the in-plane direction. The size dependence of κ shows the size effect can persist up-to 20 μm...
June 23, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28644010/atomic-layer-deposition-of-indium-gallium-oxide-thin-film-for-thin-film-transistor-applications
#7
Jiazhen Sheng, Eun Jung Park, Bonggeun Shong, Jin-Seong Park
Indium gallium oxide (IGO) thin films were deposited via atomic layer deposition (ALD) using [1,1,1-trimethyl-N-(trimethylsilyl)silanaminato]indium (InCA-1) and trimethylgallium (TMGa) as indium and gallium precursors, respectively, and hydrogen peroxide (H2O2) as the reactant. In order to clearly understand the mechanism of multicomponent ALD growth of oxide semiconductor materials, several variations in the precursor-reactant deposition cycles were evaluated. Gallium could be doped into oxide film at 200°C when accompanied by an InCA-1 pulse, and no growth of gallium oxide was observed without the simultaneous deposition of indium oxide...
June 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28643788/terahertz-saturable-absorbers-from-liquid-phase-exfoliation-of-graphite
#8
Vezio Bianchi, Tian Carey, Leonardo Viti, Lianhe Li, Edmund H Linfield, A Giles Davies, Alessandro Tredicucci, Duhee Yoon, Panagiotis G Karagiannidis, Lucia Lombardi, Flavia Tomarchio, Andrea C Ferrari, Felice Torrisi, Miriam S Vitiello
Saturable absorbers (SA) operating at terahertz (THz) frequencies can open new frontiers in the development of passively mode-locked THz micro-sources. Here we report the fabrication of THz SAs by transfer coating and inkjet printing single and few-layer graphene films prepared by liquid phase exfoliation of graphite. Open-aperture z-scan measurements with a 3.5 THz quantum cascade laser show a transparency modulation ∼80%, almost one order of magnitude larger than that reported to date at THz frequencies...
June 15, 2017: Nature Communications
https://www.readbyqxmd.com/read/28643284/hydroxyl-radical-mediated-degradation-of-diclofenac-revisited-a-computational-approach-to-assessment-of-reaction-mechanisms-and-by-products
#9
Sesil Agopcan Cinar, Asu Ziylan-Yavaş, Saron Catak, Nilsun H Ince, Viktorya Aviyente
Advanced oxidation processes (AOPs) are based on the in situ production of hydroxyl radicals (•OH) and reactive oxygen species (ROS) in water upon irradiation of the sample by UV light, ultrasound, electromagnetic radiation, and/or the addition of ozone or a semiconductor. Diclofenac (DCF), one of the emerging organic contaminants (EOC), is of environmental concern due to its abundancy in water and is known to be subjected to AOPs. The current study uses density functional theory (DFT) to elucidate the mechanisms of the reactions between •OH and DCF leading to degradation by-products, P1-P9...
June 23, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28642481/deterministic-radiative-coupling-of-two-semiconductor-quantum-dots-to-the-optical-mode-of-a-photonic-crystal-nanocavity
#10
M Calic, C Jarlov, P Gallo, B Dwir, A Rudra, E Kapon
A system of two site-controlled semiconductor quantum dots (QDs) is deterministically integrated with a photonic crystal membrane nano-cavity. The two QDs are identified via their reproducible emission spectral features, and their coupling to the fundamental cavity mode is established by emission co-polarization and cavity feeding features. A theoretical model accounting for phonon interaction and pure dephasing reproduces the observed results and permits extraction of the light-matter coupling constant for this system...
June 22, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28642432/breaking-lorentz-reciprocity-to-overcome-the-time-bandwidth-limit-in-physics-and-engineering
#11
K L Tsakmakidis, L Shen, S A Schulz, X Zheng, J Upham, X Deng, H Altug, A F Vakakis, R W Boyd
A century-old tenet in physics and engineering asserts that any type of system, having bandwidth Δω, can interact with a wave over only a constrained time period Δt inversely proportional to the bandwidth (Δt·Δω ~ 2π). This law severely limits the generic capabilities of all types of resonant and wave-guiding systems in photonics, cavity quantum electrodynamics and optomechanics, acoustics, continuum mechanics, and atomic and optical physics but is thought to be completely fundamental, arising from basic Fourier reciprocity...
June 23, 2017: Science
https://www.readbyqxmd.com/read/28641142/optical-electrical-and-ferromagnetic-studies-of-zno-fe-diluted-magnetic-semiconductor-nanoparticles-for-spintronic-applications
#12
R Elilarassi, G Chandrasekaran
In the present investigation, diluted magnetic semiconductor (Zn1-xFexO) nanoparticles with different doping concentrations (x=0, 0.02, 0.04, 0.06, and 0.08) were successfully synthesized by sol-gel auto-combustion method. The crystal structure, morphology, optical, electrical and magnetic properties of the prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis using x-rays (EDAX), ultraviolet-visible spectrophotometer, fluorescence spectroscope (FS), vibrating sample magnetometer (VSM) and broad band dielectric spectrometer (BDS)...
May 31, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28641009/metal-halide-perovskites-as-mixed-electronic-ionic-conductors-challenges-and-opportunities-from-hysteresis-to-memristivity
#13
Wolfgang Tress
Metal halide perovskites are promising candidates for many classes of different optoelectronic devices. Apart from being a semiconductor, they additionally show ionic conductivity. It expresses itself in slow response times, reversible degradation, and hysteresis in the current-voltage characteristics of solar cells. This Perspective gives a condensed overview about experiments and theory on ion migration in metal halide perovskites focusing on its effects in solar cells. Apart from being a potential stability concern for photovoltaics, ion migration paired with the excellent optoelectronic properties of this material offers opportunities for novel devices such as optically controlled memristors and switchable diodes...
June 22, 2017: Journal of Physical Chemistry Letters
https://www.readbyqxmd.com/read/28640637/designing-transmitter-ligands-that-mediate-energy-transfer-between-semiconductor-nanocrystals-and-molecules
#14
Zhiyuan Huang, Ming Lee Tang
Molecular control of energy transfer is an attractive proposition because it allows chemists to synthetically tweak various kinetic and thermodynamic factors. In this Perspective, we examine energy transfer between semiconductor nano-crystals (NCs) and π-conjugated molecules, focusing on the transmitter ligand at the organic-inorganic interface. Efficient transfer of triplet excitons across this interface allows photons to be directed for effective use of the entire solar spectrum. For example, a photon upconversion system composed of semiconductor NCs as sensitizers, bound organic ligands as transmitters, and molecular annihilators has the advantage of large, tunable absorption cross-sections across the visible and near infrared wavelengths...
June 22, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28639731/size-dependence-of-doping-via-vacancy-formation-in-copper-sulfide-nanocrystals
#15
Orian Elimelech, Jing Liu, Anna M Plonka, Anatoly I Frenkel, Uri Banin
Doping semiconductor nanocrystals (NCs) is a key yet under-explored approach for tuning their electronic properties. An important route for doping in NCs is vacancy formation. Herein, the size and concentration dependence of doping is studied in Cu2S NCs through a redox reaction with iodine leading to vacancy formation accompanied by a localized surface plasmon response. X-ray spectroscopy and diffraction reveal transformation from Cu2S to Cu depleted phases along with CuI formation. Higher efficiency of the reaction is observed for larger NCs...
June 22, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28639652/probing-single-molecule-electron-hole-transfer-dynamics-at-a-molecule-nio-semiconductor-nanocrystalline-interface
#16
Bharat Dhital, Vishal Govind Rao, H Peter Lu
Interfacial charge transfer dynamics in dye-sensitized NiO nanoparticles are being investigated for photocathodes in p-type dye-sensitized solar cells. In the photoreaction, after fast electron transfer from NiO to a molecule, the recombination of the hole in the nanoparticles with the electron in a reduced molecule plays an important role in the charge separation process and solar energy harvesting. Nevertheless, knowledge of the interfacial charge recombination (CR) rate and its mechanism is still limited due to the complex photoinduced electron and hole dynamics and lack of characterization of the inhomogeneity of the dynamics...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28639413/fully-inorganic-trihalide-perovskite-nanocrystals-a-new-research-frontier-of-optoelectronic-materials
#17
REVIEW
Xianghong He, Yongcai Qiu, Shihe Yang
All-inorganic trihalide perovskite nanocrystals (NCs) are emerging as a new class of superstar semiconductors with excellent optoelectronic properties and great potential for a broad range of applications in lighting, lasing, photon detection, and photovoltaics. This article provides an up-to-date review on the developments of fully-inorganic trihalide perovskite NCs by emphasizing their controllable solution fabrication strategies, structural phase transformation, tunable optoelectronic properties, stability, as well as their photovoltaic and optoelectronic applications...
June 22, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28638760/-bedt-ttf-2cu2-hcoo-5-an-organic-inorganic-hybrid-conducting-magnet
#18
Bin Zhang, Yan Zhang, Zheming Wang, Zengqiang Gao, Deliang Yang, Dongwei Wang, Yanjun Guo, Daoben Zhu
A dual-functional organic-inorganic hybrid (BEDT-TTF)2Cu2(HCOO)5 (1) (BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene) was obtained through the electrochemical oxidation of neutral BEDT-TTF in the presence of an ammonium salt of the one-dimensional copper-formate framework [(C2H5)3NH]2Cu2(HCOO)5 in a C6H5Cl-C2H5OH solution. Compound 1 was composed of organic donor BEDT-TTF(+0)⋅(5) in a θ-phase arrangement and Jahn-Teller distorted (4,4) grid anion sheets [Cu2(HCOO)5(-)] n with S=1/2. We identified the material as a semiconductor with values of σ300K=10(-1) S cm(-1)...
June 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28638470/bright-polymer-dots-tracking-stem-cell-engraftment-and-migration-to-injured-mouse-liver
#19
Dandan Chen, Qiong Li, Zihui Meng, Lei Guo, Ying Tang, Zhihe Liu, Shengyan Yin, Weiping Qin, Zhen Yuan, Xuanjun Zhang, Changfeng Wu
Stem cell therapy holds promise for treatment of intractable diseases and injured organs. For clinical translation, it is pivotal to understand the homing, engraftment, and differentiation processes of stem cells in a living body. Here we report near-infrared (NIR) fluorescent semiconductor polymer dots (Pdots) for bright labeling and tracking of human mesenchymal stem cells (MSCs). The Pdots exhibit narrow-band emission at 775 nm with a quantum yield of 22%, among the highest value for various NIR probes. The Pdots together with a cell penetrating peptide are able to track stem cells over two weeks without disturbing their multipotent properties, as confirmed by the analyses on cell proliferation, differentiation, stem-cell markers, and immunophenotyping...
2017: Theranostics
https://www.readbyqxmd.com/read/28638150/strain-balanced-type-ii-superlattices-for-efficient-multi-junction-solar-cells
#20
A Gonzalo, A D Utrilla, D F Reyes, V Braza, J M Llorens, D Fuertes Marrón, B Alén, T Ben, D González, A Guzman, A Hierro, J M Ulloa
Multi-junction solar cells made by assembling semiconductor materials with different bandgap energies have hold the record conversion efficiencies for many years and are currently approaching 50%. Theoretical efficiency limits make use of optimum designs with the right lattice constant-bandgap energy combination, which requires a 1.0-1.15 eV material lattice-matched to GaAs/Ge. Nevertheless, the lack of suitable semiconductor materials is hindering the achievement of the predicted efficiencies, since the only candidates were up to now complex quaternary and quinary alloys with inherent epitaxial growth problems that degrade carrier dynamics...
June 21, 2017: Scientific Reports
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