A5064547074- Ion-surface interactions and analysis
- Semiconductor materials and devices
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor Quantum Structures and Devices
- Silicon and Solar Cell Technologies
- Thin-Film Transistor Technologies
- X-ray Spectroscopy and Fluorescence Analysis
- Silicon Nanostructures and Photoluminescence
- Semiconductor materials and interfaces
- GaN-based semiconductor devices and materials
- Terahertz technology and applications
- Geophysics and Sensor Technology
- Pulsars and Gravitational Waves Research
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Photonic and Optical Devices
- Advanced Surface Polishing Techniques
- Cold Atom Physics and Bose-Einstein Condensates
- Nanowire Synthesis and Applications
- Metal and Thin Film Mechanics
- Electron and X-Ray Spectroscopy Techniques
- Glass properties and applications
- Optical Coatings and Gratings
- Advanced Semiconductor Detectors and Materials
- Quantum Dots Synthesis And Properties
Université de Montréal
2012-2024
Regroupement Québécois sur les Matériaux de Pointe
2006-2020
Agriculture and Agri-Food Canada
2002
Polytechnique Montréal
1998
The structure factor $S(Q)$ of high purity amorphous Si membranes prepared by ion implantation was measured over an extended $Q$ range ( $0.03--55{\AA{}}^{\ensuremath{-}1}$). Calculation the first neighbor shell coordination ${C}_{1}$) as a function maximum indicates that measurement out to at least $40{\AA{}}^{\ensuremath{-}1}$ is required reliably determine radial distribution (RDF). A $2%$ change in ${C}_{1}$ and subtle changes rest RDF were observed upon annealing, consistent with point...
Medium and high-energy x-ray diffraction has been used to study the atomic structure of pure amorphous Si prepared by MeV implantation into crystalline silicon. Both as-implanted annealed samples were studied. The inelastically scattered x rays removed fitting energy spectrum for rays. scattering factor silicon, previously known reliably up 20 ${\mathrm{\AA{}}}^{\mathrm{\ensuremath{-}}1}$, extended 55 ${\mathrm{\AA{}}}^{\mathrm{\ensuremath{-}}1}$. radial distribution function Si, before...
The sensitivity of current and planned gravitational wave interferometric detectors is limited, in the most critical frequency region around 100 Hz, by a combination quantum noise thermal noise. latter dominated Brownian noise: motion originating from elastic energy dissipation dielectric coatings used interferometer mirrors. material property characterized mechanical loss angle. We have identified mixtures titanium dioxide (TiO$_2$) germanium (GeO$_2$) that show internal dissipations at...
The compositional dependence of the fundamental bandgap pseudomorphic GaAs1−xBix layers on GaAs substrates is studied at room temperature by optical transmission and photoluminescence spectroscopies. All films (0 ≤ x 17.8%) show direct bandgaps, which decrease with increasing Bi content, closely following density functional theory predictions. smallest measured 0.52 eV (∼2.4 μm) 17.8% Bi. Extrapolating a fit to data, predicted reach 0 35% Below bandgap, exponential absorption band tails are...
New features of the nanoscale structure amorphous (a)-Si produced by ion-implantation-induced amorphization crystalline (c)-Si have been determined technique small-angle x-ray scattering (SAXS). Si ion energies up to 17 MeV were used generate a thick layer (8 μm) on c-Si wafer enable SAXS measurements. As-implanted and thermally annealed (up 540 °C) a-Si studied. No nanovoids detected within sensitivity 0.1 vol %, but atomic-scale measurable diffuse signal that decreased with increasing...
The effects of reactive and sputtering oxygen partial pressure on the structure, stoichiometry optical properties hafnium oxide (HfO2) thin films have been systematically investigated. electron cyclotron resonance ion beam deposition (ECR-IBD) technique was used to fabricate JGS-3 fused silica substrates. amorphous structure HfO2 were determined by X-ray Diffraction. Energy-dispersive Spectroscopy Rutherford Backscattering Spectrometry carried out for composition analysis, where this...
Abstract Blistering is a phenomenon sometimes observed in sputtered-deposited thin films but seldom investigated detail. Here, we consider the case of titania-doped germania (TGO)/silica multilayers deposited by ion beam sputtering. TGO candidate as high refractive index material Bragg mirrors for next iteration gravitational waves detectors. It needs to be annealed at 600 ∘ C 100 h order reach desired relaxation state. However under some growth conditions, 52-layer TGO/silica stacks,...
Glasses are nonequilibrium solids with properties highly dependent on their method of preparation. In vapor-deposited molecular glasses, structural organization could be readily tuned deposition rate and substrate temperature. Here, we show that the atomic arrangement strong network-forming GeO2 glass is modified at medium range (<2 nm) through vapor elevated temperatures. Raman spectral signatures distinctively population six-membered GeO4 rings increases Deposition near transition...
Upgrades to ground-based gravitational-wave observatories will require mirror coatings with reduced thermal noise, enabling improved detector sensitivity and extended astrophysical reach. Recent studies have shown that optical utilising amorphous materials exhibit a larger fraction of corner-sharing between adjacent structural units metal-centered polyhedra are promising route for reducing mechanical dissipation thus noise at room temperature. We report on multilayer fabricated using...
Coating thermal noise is one of the dominant sources in current gravitational wave detectors and ultimately limits their ability to observe weaker or more distant astronomical sources. This Letter presents investigations TiO_{2} mixed with SiO_{2} (TiO_{2}:SiO_{2}) as a coating material. We find that, after heat treatment for 100 h at 850 °C, highly reflective comprising TiO_{2}:SiO_{2} reduces 76% levels Advanced LIGO Virgo detectors-with potential reaching 45%, if we assume mechanical loss...
We investigated the microstructural transformations during hydrogen ion-induced splitting of GaN thin layers. Cross-sectional transmission electron microscopy and positron annihilation spectroscopy data show that implanted region is decorated with a high density 1–2nm bubbles resulting from vacancy clustering implantation. These nanobubbles persist up to 450°C. Ion channeling strong dechanneling enhancement in this temperature range tentatively attributed strain-induced lattice distortion....
A multiple-energy, high fluence, MeV Fe ion implantation process was applied at 83 K to heavily damage a low band gap (0.79 eV) epitaxial InGaAsP layer. Optimal rapid thermal annealing conditions were found and produced fast photoconductor with resistivity (up 2500 Ωcm) Hall mobility around 400 cm2V−1s−1. Short photocarrier trapping times (0.3 ps – 3 ps) observed via transient differential reflectivity measurements. Furthermore, photoconductive terahertz devices coplanar electrodes...
Irradiation of InP with MeV Se ions directed a few degrees off the surface normal leads to lateral displacement implanted material. Adjacent regions that are not irradiated remain unaffected. The dependence on ion energy and its directionality strongly suggest effect is caused by momentum transfer from solid. amount displaced material as function beam or angle incidence can be described simple model incorporating shear stress, applied target slows down, radiation enhanced viscosity.
The $^{15}\mathrm{O}$($\ensuremath{\alpha},\ensuremath{\gamma}$)$^{19}\mathrm{Ne}$ reaction plays a role in the ignition of type I x-ray bursts on accreting neutron stars. lifetimes states $^{19}\mathrm{Ne}$ above $^{15}\mathrm{O}$$+\ensuremath{\alpha}$ threshold 3.53 MeV are important inputs to calculations astrophysical rate. These levels were populated $^{3}\mathrm{He}$($^{20}\mathrm{Ne}$,$\ensuremath{\alpha}$)$^{19}\mathrm{Ne}$ at $^{20}\mathrm{Ne}$ beam energy 34 MeV. six measured with...
We present a detailed study of the comparative thermal evolutions H- and D-related defects in silicon implanted with $2\ifmmode\times\else\texttimes\fi{}{10}^{16}\phantom{\rule{0.3em}{0ex}}\mathrm{H}$ or $\mathrm{D}∕{\mathrm{cm}}^{2}$, coimplanted $0.25\ifmmode\times\else\texttimes\fi{}{10}^{16}\phantom{\rule{0.3em}{0ex}}\mathrm{He}∕{\mathrm{cm}}^{2}$ $0.7\ifmmode\times\else\texttimes\fi{}{10}^{16}\phantom{\rule{0.3em}{0ex}}\mathrm{H}∕{\mathrm{cm}}^{2}$, both orders. By using ion channeling,...
High energy x-ray diffraction measurements of pure amorphous Ge were made and its radial distribution function (RDF) was determined at high resolution, revealing new information on the atomic structure semiconductors. Fine in second peak RDF provides evidence that a fraction third neighbors are closer than some neighbors; taking this into account leads to narrow tetrahedral bond angles, $(8.5\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode^\circ\else\textdegree\fi{}$. A small which appears near 5...
Abstract One of the main noise sources in current gravitational-wave detectors is thermal high-reflectivity coatings on interferometer optics. Coating dominated by mechanical loss high-refractive index material within coating stacks, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi>Ta</mml:mi> <mml:mn>2</mml:mn> </mml:msub> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>5</mml:mn> </mml:mrow> </mml:math> mixed with...
The Doppler-shift attenuation method was applied to measure the lifetime of 4.03 MeV state in $^{19}\mathrm{Ne}$. By utilizing a $^{3}\mathrm{He}$-implanted Au foil as target, populated using $^{20}\mathrm{Ne}$($^{3}\mathrm{He}$, $\ensuremath{\alpha}$)$^{19}\mathrm{Ne}$ reaction inverse kinematics at $^{20}\mathrm{Ne}$ beam energy 34 MeV. De-excitation \ensuremath{\gamma} rays were detected coincidence with \ensuremath{\alpha} particles. At 1\ensuremath{\sigma} level, determined be...
In this paper we present experiments aimed at understanding three different phenomena that deform the surface of solids during irradiation by 24-MeV heavy ions. These are (1) density changes; (2) anisotropic growth, which describes thinning a solid along normal to and its growth in plane without (3) lateral mass transport. Lateral transport occurs only if ion beam is no longer perpendicular surface. It consists displacement some implanted material direction component velocity parallel...
In this work we compare the characteristics of asymmetrically excited small-aperture antenna-type pulsed terahertz emitters fabricated using an ion implantation process. Our photoconductive materials consist high resistivity GaAs substrates. Multienergy implantations arsenic (1.2 and 2MeV) oxygen (180, 450, 700keV) have been used to obtain almost uniform density vacancies over optical absorption depth in bulk Terahertz pulses are generated by exciting our devices with ultrashort laser...