A5035874630- Electron and X-Ray Spectroscopy Techniques
- 2D Materials and Applications
- Advanced Electron Microscopy Techniques and Applications
- Nanowire Synthesis and Applications
- Quantum Dots Synthesis And Properties
- Diamond and Carbon-based Materials Research
- Chalcogenide Semiconductor Thin Films
- Electronic and Structural Properties of Oxides
- Perovskite Materials and Applications
- Semiconductor Quantum Structures and Devices
- Force Microscopy Techniques and Applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Plasmonic and Surface Plasmon Research
- Ion-surface interactions and analysis
- Ga2O3 and related materials
- GaN-based semiconductor devices and materials
- Graphene research and applications
- Integrated Circuits and Semiconductor Failure Analysis
- Molecular Junctions and Nanostructures
- Advancements in Semiconductor Devices and Circuit Design
- Semiconductor materials and devices
- ZnO doping and properties
- Boron and Carbon Nanomaterials Research
- Metal and Thin Film Mechanics
- Transition Metal Oxide Nanomaterials
Université Paris-Saclay
2016-2025
Laboratoire de physique des Solides
2016-2025
Centre National de la Recherche Scientifique
2016-2025
Texas A&M University
2020
California State University, Northridge
2020
Université Paris-Sud
2012-2019
National Institute of Advanced Industrial Science and Technology
2014-2016
Centre Hospitalier d'Orsay
2015
Universidade Estadual de Campinas (UNICAMP)
2008-2013
Brazilian Synchrotron Light Laboratory
2008-2010
To date, quantum sources in the ultraviolet (UV) spectral region have been obtained only semiconductor dots. Color centers wide bandgap materials may represent a more effective alternative. However, quest for UV emitters bulk crystals faces difficulty of combining an efficient excitation/detection optical setup with capability addressing individual color potentially highly defective materials. In this work we overcome limit by employing original experimental coupling cathodoluminescence...
Stable emission in glass Lead halide perovskites can exhibit bright, narrow band photoluminescence but have stability issues related to formation of inactive phases and the loss lead ions. Hou et al . show that black, photoactive phase cesium iodide be stabilized by forming a composite with glassy metal-organic framework through liquid-phase sintering. The is at least two orders magnitude greater than pure perovskite. stabilizes perovskite under high laser excitation, about 80% was...
We have measured the second order correlation function [g^{(2)}(τ)] of cathodoluminescence intensity resulting from excitation by fast electrons defect centers in wide band-gap semiconductor nanocrystals diamond and hexagonal boron nitride. show that g^{(2)}(τ) multiple is dominated a large, nanosecond zero-delay bunching (g^{(2)}(0)>30), stark contrast to their flat photoluminescence function. developed model showing this can be attributed synchronized emission several excited same electron...
Polaritons are compositional light-matter quasiparticles that have enabled remarkable breakthroughs in quantum and nonlinear optics, as well material science. Recently, plasmon–exciton polaritons (plexcitons) been realized hybrid systems composed of transition metal dichalcogenide (TMDC) materials nanoparticles, expanding polaritonic concepts to room temperature nanoscale also benefit from the exotic properties TMDC materials. Despite enormous progress understanding TMDC-based plexcitons...
Spatially resolved electron-energy-loss spectroscopy (EELS) is performed at diffuse interfaces between ${\mathrm{MoS}}_{2}$ and ${\mathrm{MoSe}}_{2}$ single layers. With a monochromated electron source (20 meV) we successfully probe excitons near the interface by obtaining low loss spectra nanometer scale. The exciton maps clearly show variations even with 10 nm separation measurements; consequently, optical band gap can be measured nanometer-scale resolution, which 50 times smaller than...
Imaging polariton dynamics Two-dimensional (2D) materials can confine light to volumes much shorter than the wavelength, and, together, long propagation lengths make them attractive for developing nanophotonic platforms. Characterizing spatiotemporal control of 2D wave packets has been hindered same reasons that their potential applications exciting: They have extremely small wavelengths and are strongly confined inside material. Kurman et al. developed a new pump-probe technique based on...
Silver, king among plasmonic materials, features low inelastic absorption in the visible-infrared (vis-IR) spectral region compared to other metals. In contrast, copper is commonly regarded as too lossy for actual applications. Here, we demonstrate vis-IR plasmons with quality factors >60 long nanowires (NWs), determined by electron energy-loss spectroscopy. We explain this result noticing that most of electromagnetic energy these lies outside metal, thus becoming less sensitive absorption....
Following the lifespan of optical excitations from their creation to decay into photons is crucial in understanding materials properties. Macroscopically, techniques such as photoluminescence excitation spectroscopy provide unique information on photophysics with applications diverse quantum optics or photovoltaics. Materials and emission pathways are affected by nanometer scale variations directly impacting devices performances. However, they cannot be accessed, despite techniques,...
We report on the experimental demonstration of single-photon state generation and characterization in an electron microscope. In this aim we have used low intensity relativistic (energy between 60 100 keV) electrons beams focused a ca. 1 nm probe to excite diamond nanoparticles. This triggered individual neutral nitrogen-vacancy centers emit photons which could be gathered sent Hanbury Brown-Twiss interferometer. The detection dip correlation function at small time delays clearly...
The strong excitonic emission of hexagonal boron nitride (h-BN) makes this material one the most promising candidate for light emitting devices in far ultraviolet (UV). However, single excitons occur only perfect monocrystals that are extremely hard to synthesize, while regular h-BN samples present a complex spectrum with several additional peaks. microscopic origin these emissions has not yet been understood. In work we address problem using an experimental and theoretical approach combines...
Abstract Electroreduction of CO 2 to is one the simplest ways valorise as a source carbon. Herein, cheap, robust, Cu‐based hybrid catalyst consisting polymer Cu phthalocyanine coated on carbon nanotubes, which proved be selective for production (80 % faradaic yield) at relatively low overpotentials, was developed. Polymerisation shown have drastic effect selectivity reaction because molecular instead proton reduction under same conditions. Although material only showed isolated sites in...
We investigated experimentally and theoretically the valence-band structure of wurtzite InP nanowires. The phase, which usually is not stable for III-V phosphide compounds, has been observed in present results on electronic properties these nanowires using photoluminescence excitation technique. Spectra from an ensemble show three clear absorption edges separated by 44 meV 143 meV, respectively. band are attributed to excitonic absorptions involving distinct valence-bands labeled: A, B, C....
Here we report the spectrally and spatially resolved cathodoluminescence of diamond nanoparticles using focused fast electron beams in a transmission microscope. We demonstrate possibility quickly detecting various individual colour centres different kinds on wide areas (several micrometres square) contained separated by subwavelength distances. Among them, containing one or more neutral nitrogen-vacancy (NV(0)) intensity maxima have been seen, attributable to emitters. Thanks spatial...
Abstract It is generally believed that CO 2 electroreduction to multi‐carbon products such as ethanol or ethylene may be catalyzed with significant yield only on metallic copper surfaces, implying large ensembles of atoms. Here, we report an inexpensive Cu‐N‐C material prepared via a simple pyrolytic route exclusively feature single atoms CuN 4 coordination environment, atomically dispersed in nitrogen‐doped conductive carbon matrix. This achieves aqueous at Faradaic 55 % under optimized...
Atomic vibrations and phonons are an excellent source of information on nanomaterials that we can access through a variety methods including Raman scattering, infrared spectroscopy, electron energy-loss spectroscopy (EELS). In the presence plasmon local field, strongly modified and, in particular, their dipolar strengths highly enhanced, thus rendering scattering extremely sensitive techniques. Here, experimentally demonstrate interaction between relativistic vibrational modes nanostructures...
Structural, electronic, and chemical nanoscale modifications of transition metal dichalcogenide monolayers alter their optical properties. A key missing element for complete control is a direct spatial correlation response to due the large gap in resolution between spectroscopy nanometer-resolved techniques. Here, we bridge this by obtaining properties using electron at cryogenic temperatures, specifically energy loss absorption cathodoluminescence emission, which are then directly...
The synergy between free electrons and light has recently been leveraged to reach an impressive degree of simultaneous spatial spectral resolution, enabling applications in microscopy quantum optics. However, the required combination electron optics injection into spectrally narrow modes arbitrary specimens remains a challenge. Here, we demonstrate microelectronvolt resolution with sub-nanometer probe photonic quality factors as high 104. We rely on mode matching tightly focused laser beam...
The dependence of excited electron–hole state properties on the size their host semiconducting nanostructures is seed for a plethora applications such as light-emitting diodes (LEDs) and photovoltaic cells. However, inability state-of-the art, diffraction-limited optical techniques to probe lifetime variations at scale individual quantum emitters precludes full understanding nanostructures' properties. Here, we demonstrate measurement lifetimes few angströms thick separated by only...
The excitonic states of transition metal dichacolgenide (TMD) monolayers are heavily influenced by their external dielectric environment based on the substrate used. In this work, various wide bandgap materials, namely hexagonal boron nitride (\textit{h}-BN) and amorphous silicon (Si$_3$N$_4$), under different configurations as support or encapsulation material for WS$_2$ investigated to disentangle factors contributing inhomogeneous broadening exciton absorption lines in TMDs using electron...
The stellar optoelectronic properties of metal halide perovskites provide enormous promise for next-generation optical devices with excellent conversion efficiencies and lower manufacturing costs. However, there is a long-standing ambiguity as to whether the perovskite surface/interface (e.g. structure, charge transfer or source off-target recombination) bulk are more determining factor in device performance. Here we fabricate an array CsPbI3 crystal hybrid glass composites by sintering...
Control over the optical properties of atomically thin two-dimensional (2D) layers, including those transition metal dichalcogenides (TMDs), is needed for future optoelectronic applications. Here, near-field coupling between TMDs and graphene/graphite used to engineer exciton line shape charge state. Fano-like asymmetric spectral features are produced in WS