A5040691919- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- ZnO doping and properties
- Quantum and electron transport phenomena
- Ga2O3 and related materials
- Semiconductor materials and devices
- Quantum Dots Synthesis And Properties
- Strong Light-Matter Interactions
- Electronic and Structural Properties of Oxides
- Silicon Nanostructures and Photoluminescence
- Nanowire Synthesis and Applications
- Quantum Information and Cryptography
- Advanced Semiconductor Detectors and Materials
- X-ray Diffraction in Crystallography
- Mechanical and Optical Resonators
- Advanced Photocatalysis Techniques
- Crystallization and Solubility Studies
- Quantum optics and atomic interactions
- TiO2 Photocatalysis and Solar Cells
- Luminescence Properties of Advanced Materials
- 2D Materials and Applications
- Metal-Organic Frameworks: Synthesis and Applications
- Photonic and Optical Devices
- Photocathodes and Microchannel Plates
- Magnetic and transport properties of perovskites and related materials
Centre National de la Recherche Scientifique
2009-2023
Université de Strasbourg
2010-2023
Institut de Physique et Chimie des Matériaux de Strasbourg
2012-2023
Canadian Nautical Research Society
2014-2015
Université de Montpellier
1999-2001
Time-resolved photoluminescence (PL), at T=8 K, is used to study a graded-width InGaN/GaN quantum well. Across the sample, well width continuously varies from ∼5.5 2.0 nm corresponding PL peak energies varying between and 2.9 eV decay rates covering four orders of magnitude. The plot times versus very fitted by calculation electron–hole recombination probability width. only fitting parameter electric field in well, which we find equal 2.45±0.25 MV/cm, excellent agreement with experimental...
We present evidence of all-optical trion generation and emission in pristine single-walled carbon nanotubes (SWCNTs). Luminescence spectra, recorded on individual SWCNTs over a large cw excitation intensity range, show peaks redshifted with respect to the bright exciton peak. Clear chirality dependence is observed for 22 separate SWCNT species, allowing determination electron-hole exchange interaction binding energy contributions. data together ultrafast pump-probe experiments...
We present a study of free carrier photogeneration and multicarrier bound states, such as biexcitons trions (charged excitons), in semiconducting single-walled carbon nanotubes. Pump-and-probe measurements performed with fs pulses reveal the effects strong Coulomb interactions between carriers on their dynamics. Biexciton formation by optical transition from exciton population results an induced absorption line (binding energy 130 meV). Exciton-exciton annihilation process is shown to evolve...
We propose an analysis of the emission properties anatase and rutile titanium dioxide (TiO2) that emphasizes role strong electron-phonon interaction. performed measurements photoluminescence (PL) spectra bulk monocrystals under continuous wave-laser excitation their temperature dependence. show in both rutile, weakly bound self-trapped excitons are actually made out from carrier polarons give rise to a broad band visible spectral range. The thermal activation motion allows hopping distant...
We demonstrate that a single photoexcited InGaAs semiconductor quantum dot (QD) grown by organo-metallic chemical vapor deposition on prepatterned substrates emits one photon at time, with no uncontrolled background emission, making it an excellent emitter. Moreover, our fabrication technique offers complete site control and small inhomogeneous broadening of QD arrays, which is essential for the practical implementation QDs in efficient solid-state emitting devices.
We investigated the structural and optical properties of Eu-doped ZnO thin films made by sol-gel technique magnetron reactive sputtering on Si (100) substrate. The elaborated process are polycrystalline while show a strongly textured growth along c-axis. X-ray diffraction patterns transmission electron microscopy analysis that all samples free spurious phases. presence Eu2+ Eu3+ into matrix has been confirmed x-ray photoemission spectroscopy. This means small fraction Europium substitutes...
We collect a large number of experimental data from various sources to demonstrate that free-standing (FS) oxide-passivated silicon nanocrystals (SiNCs) exhibit considerably blueshifted emission, by 200 meV on average, compared those prepared as matrix-embedded (ME) ones the same size. This is suggested arise compressive strain, exerted their matrix, which plays an important role in light-emission process; this strain has been neglected up now opposed impact quantum confinement or surface...
The luminescence of rare earths in CeO<sub>2</sub>is sensitized by intrinsic Ce<sup>3+</sup>ions.
The present study focuses on the structural and optical properties of ZnO thin films fabricated by sol-gel process spin coated onto Si (100) quartz substrates. have a hexagonal wurtzite structure with grain size about 50 nm. x-ray photoelectron spectroscopy measurements reveal presence Zn2+ zinc hydroxyl groups at film. Optical were studied photoluminescence (PL) absorption low room temperatures. spectrum is dominated sharp excitonic peak At temperature, PL observations show two transitions:...
Silicon nanocrystals (SiNCs) smaller than 5 nm are a material with strong visible photoluminescence (PL). However, the physical origin of PL, which, in case oxide-passivated SiNCs, is typically composed slow-decaying red–orange band (S-band) and fast-decaying blue–green (F-band), still not fully understood. Here we present interpretation F-band based on results an experimental study, which combine temperature (4–296 K), temporally (picosecond resolution) spectrally resolved luminescence...
We report on photon correlation measurements a single quantum dot formed at fluctuations of the interface GaAs/GaAlAs well. demonstrate that under pulsed nonresonant excitation, emits per pulse. This shows after emission, there is no refill by nearby two-dimensional reservoir delocalized states. The possibility delivering Fourier transform limited photons makes this system good candidate for exciton- and photon-based information processing schemes.
We compare several InGaN-based low-dimensional systems, by time-resolved photoluminescence (PL), versus temperature (8&lt;T&lt;280 K). investigate the influence of growing or not an AlGaN barrier on top active layer. address differences between quantum wells and boxes 5–10 nm in diameter 2 height. Our results are consistent with carrier localization potential fluctuations spatial extension much smaller than size boxes. Growing reduces mobility fluctuations, thus maintaining effective...
The present study focused on ZnO thin films fabricated by sol–gel process and spin coated onto Si (1 0 0) quartz substrates. have a hexagonal würtzite structure with grain diameter about 50 nm. Optical properties were determined photoluminescence (PL) absorption spectroscopy. spectrum is dominated sharp excitonic peak at room low temperatures. At temperature, two transitions observed PL. One near to the prohibited energy band in ultraviolet (UV) region other centered 640 nm, characteristic...
Sputtered ZnO thin films doped with Nd present efficient down-shifting properties.
Silicon nanocrystals (Si-ncs) of sufficiently small size, emitting luminescence at short wavelengths (which implies the occurrence quasi-direct radiative recombination) and being densely packed in a planar thin film ensures stimulated emission (StE) lifetime) can become suitable active material for observation StE visible region. In this paper, we describe fabrication method nanostructures type, based on enhanced electrochemical etching silicon wafers followed by embedding porous grains into...
We report the observation of positive optical gain in silicon nanocrystals (Si-nc) embedded nitride measured by variable stripe length technique. evidence onset stimulated emission and coefficients up to 52 cm−1 at highest excitation power (6.5 W/cm2). Photoluminescence dynamics presents two distinct recombination lifetimes nanosecond microsecond ranges. This was interpreted terms fast carrier trapping nitrogen-induced localized states Si-nc surface subsequent slow radiative recombination,...
Embedding luminescent rare earth ions into transparent oxides such as ZnO is a well-known approach to functionalize the material by adding photon-management properties. In this paper we present detailed study of luminescence properties and energy level structure Pr3+ Yb3+ embedded in thin films deposited magnetron reactive sputtering. Careful photoluminescence excitation spectra allowed identifying locating almost all excited levels ions. Thus, an complete electronic diagram these crystal...
GaN epilayers and GaN/AlGaN quantum wells (QWs) were grown by molecular beam epitaxy on GaN(0001) single crystal substrates. Transmission electron microscopy (TEM) was used to assess the quality of homoepitaxial layers. A dislocation density less than 105 cm−2 is deduced from TEM imaging. Low temperature (1.8 K) photoluminescence (PL) reveals PL linewidths as low 0.3 meV for bound excitons. The integrated intensity variation between 10 300 K compared that observed a typical heteroepitaxial...
Abstract Solvo‐ionothermal reactions were run between cobalt acetate or zinc and 1,3‐bis(carboxymethyl)imidazolium chloride ([(MimCO 2 H) ][Cl]). These led to two isostructural metal–organic frameworks (MOFs). compounds, [(MimCO ) ] Co Zn, obtained as single crystals, their structures determined by single‐crystal X‐ray diffraction. analogs have a 2D framework consisting of the stacking layers formed interconnection rings containing ligands metal ions. The structural thermal properties...
We demonstrate theoretically and experimentally that four-wave mixing processes obey phase-matching conditions determine not only the conservation of photon energy k-momentum but also orbital angular momentum light. report on time-resolved experiments performed a CdTe/CdZnTe quantum well in both noncollinear collinear configurations with Laguerre-Gauss beams. They polarization wave which is induced material keeps memory excitation pulse momentum. show configuration, large acceptance opens up...
The synthesis and characterization of six new lanthanide networks [Ln(L)(ox)(H 2 O)] with Ln = Eu 3+ , Gd Tb Dy Ho Yb is reported. They were synthesized by solvo-ionothermal reaction nitrate Ln(NO 3 ) · x H O the 1,3-bis(carboxymethyl)imidazolium [HL] ligand oxalic acid (H ox) in a water/ethanol solution. crystal structure these compounds has been solved on single crystals magnetic luminescent properties have investigated relying intrinsic ions. synthetic strategy extended to mixed leading...
Previous experimental studies have allowed us to observe peculiar localization effects of excitons in GaN/AlGaN quantum wells grown by MBE, as well efficient nonradiative inter-well carrier transfers. In this work, we use the envelope-function approximation calculate exciton energies and wave functions. We show that typical spatial extension electron hole can itself explain transfer processes, mainly because, due its large effective mass, in-plane is smaller than average distance between two...