Hybrid MBE-CBE Growth and Characterization of Al 0.48 In 0.52 As on InP(100) for avalanche photodiode applications Motivation

International audienceIn this work, we demonstrate the epitaxial growth of high quality, low strain and low background doping of Al0.48In0.52As at 500°C on Fe-doped semi-insulating InP(100) substrate by using hybrid MBE-CBE technique. The precursors that were used are: solid aluminum, solid indium, TriMethylIndium (TMIn) and thermally cracked arsine. Using Nomarski, we observed smooth surfaces for the as grown layers. High-Resolution X-ray Diffraction (HR-XRD) in the vicinity of the (004) reflexion shows a lattice mismatch in the range -137 to 127ppm. The carrier density of undoped layers, obtained by Hall measurement at room temperature, is as low as 3E+15 cm-3 which is three orders of magnitude lower than the identical layers grown by organometallics sources. Photoluminescence (PL) for Al0.48In0.52As at low temperature (LT) shows a good optical quality. The quality and purity of the alloys grown here are compatible with high performance APD for optical communication

Optical spatial solitons at the interface between two dissimilar periodic media: Theory and experiment

Discrete spatial solitons traveling along the interface between two dissimilar one-dimensional arrays of waveguides were observed for the first time. Two interface solitons were found theoretically, each one with a peak in a different boundary channel. One evolves into a soliton from a linear mode at an array separation larger than a critical separation where-as the second soliton always exhibits a power threshold. These solitons exhibited different power thresholds which depended on the characteristics of the two lattices. For excitation of single channels near and at the boundary, the evolution behavior with propagation distance indicates that the solitons peaked near and at the interface experience an attractive potential on one side of the boundary, and a repulsive one on the opposite side. The power dependence of the solitons at variable distance from the boundary was found to be quite different on opposite sides of the interface and showed evidence for soliton switching between channels with increasing input power

Traitement de la fondation de moraine du barrage LG-3

A section of the LG-3 dam, one of the major hydroelectric structures of the James Bay development, is founded on a thick deposit of semi-impervious glacial till. An adequate foundation treatment was necessary to cope with the seepage problem.This paper describes the foundation conditions and the studies leading to the design of the dam on the till deposit, where an upstream blanket and cut off have been combined with a downstream toe drain in the typical cross section. An instrumentation program will allow the monitoring of the behaviour of the dam and its foundation so as to detect any anomaly that might develop. [Journal translation] </jats:p

Verifying patient identity and site of surgery: improving compliance with protocol by audit and feedback

BACKGROUND: The potential severity of wrong patient/procedure/site of surgery and the view that these events are avoidable, make the prevention of such errors a priority. An intervention was set up to develop a verification protocol for checking patient identity and the site of surgery with periodic audits to measure compliance while providing feedback. ASSESSMENT OF PROBLEM: A nurse auditor performed the compliance audits in inpatients and outpatients during three consecutive 3-month periods and three 1-month follow-up periods; 11 audit criteria were recorded, as well as reasons for not performing a check. STRATEGY FOR CHANGE: The nurse auditor provided feedback to the health professionals, including discussion of inadequate checks. RESULTS: 1,000 interactions between patients and their anaesthetist or nurse anaesthetist were observed. Between the first and second audit periods compliance with all audit criteria except "surgical site marked" noticeably improved, such as the proportion of patients whose identities were checked (62.6% to 81.4%); full compliance with protocol in patient identity checks (9.7% to 38.1%); proportion of site of surgery checks carried out (77.1% to 92.6%); and full compliance with protocol in site of surgery checks (32.2% to 52.0%). Thereafter, compliance was stable for most criteria. The reason for failure to perform checks of patient identity or site of surgery was mostly that the anaesthetist in charge had seen the patient at the preanaesthetic consultation. LESSONS AND MESSAGES: By combining the implementation of a verification protocol with periodic audits with feedback, the intervention changed practice and increased compliance with patient identity and site of surgery checks. The impact of the intervention was limited by communication problems between patients and professionals, and lack of collaboration with surgical services

Second Harmonic Generation in AlGaAs Nanowaveguides

In this paper, we investigate semiconductor nanowaveguides (i.e. ridge waveguides with core-widths narrower than 1 μm) intended to act as novel optical light sources through nonlinear wavelength/frequency conversion. In particular, numerical calculations have been performed in order to design suitable photonic devices (fabricated in the AlGaAs/GaAs platform) capable of high efficiency second harmonic generation. Particular interest has been dedicated to the effective conversion of optical signals from 1520-1600 nm (the third telecom window) down to 760-800 nm. We demonstrate that the output wavelength (resulting from modal phase-matching) can be dynamically tuned by proper adjustment of the temperature and/or geometrical parameters of the waveguides. In addition, by changing the waveguide width it is also possible to modify the device dispersion characteristics, giving the possibility to work in the region of anomalous dispersion and thus allowing for the generation of temporal solitons

"Fabrication of high resistivity cold-implanted InGaAsP photoconductors for efficient pulsed terahertz device"

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Second Harmonic Generation in AlGaAs Nanowaveguides

In this paper, we investigate semiconductor nanowaveguides (i.e. ridge waveguides with core-widths narrower than 1 μm) intended to act as novel optical light sources through nonlinear wavelength/frequency conversion. In particular, numerical calculations have been performed in order to design suitable photonic devices (fabricated in the AlGaAs/GaAs platform) capable of high efficiency second harmonic generation. Particular interest has been dedicated to the effective conversion of optical signals from 1520-1600 nm (the third telecom window) down to 760-800 nm. We demonstrate that the output wavelength (resulting from modal phase-matching) can be dynamically tuned by proper adjustment of the temperature and/or geometrical parameters of the waveguides. In addition, by changing the waveguide width it is also possible to modify the device dispersion characteristics, giving the possibility to work in the region of anomalous dispersion and thus allowing for the generation of temporal solitons

"Fabrication of high resistivity cold-implanted InGaAsP photoconductors for efficient pulsed terahertz device"

International audienc

Graphene-porous semiconductor nanocomposites scalable synthesis for energy applications

Abstract The aim of this work is to develop a cost effective and scalable fabrication process for graphene-enhanced porous semiconductor nanocomposite (GPNC). This class of materials combines the remarkable properties of graphene with the unique properties of porous semiconductors, such as porous silicon (PSi) and porous germanium (PGe). The experimental results show that these nanocomposites are chemically resistant to most of the commonly used microfabrication solutions and have enhanced electrical and thermal properties. Besides, we demonstrate the potential of graphene-porous germanium nanocomposite (GPGNC) for energy storage application.</jats:p

Duplicated design to further improve III-V solar cell efficiency at ultra-high concentration factors (>1000 suns)

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