318 research outputs found
Two-photon interference from a quantum emitter in hexagonal boron nitride
No full textData from all figures from the article:
C. Fournier, S. Roux, K. Watanabe, T. Taniguchi, S. Buil, J. Barjon, J.-P. Hermier, A. Delteil,
"Two-photon interference from a quantum emitter in hexagonal boron nitride",
Phys. Rev. Applied 19, L041003 (2023).
Fig.1: spectroscopy of the quantum emitter studied in the publication.
Fig. 2: time-resolved photon counting data. (b) Fluorescence decay. (c) Hanbury Brown and Twiss correlations. (d) Hong-Ou-Mandel correlations in parallel and orthogonal configurations.
Fig. 3a: HOM visibility as a function of the time filter width.
Fig. 3b: simulation of the visibility decay as a function of the emitter dephasing time
Archbishop of Meurx at Baroy, a town shelled by German artillery.
No full textStereoview of four men and a woman standing in front of ruined buildings in Barjon. One of the men, dressed in Catholic robes, is the Archbishop
Distinguishing Different Stackings in Layered Materials via Luminescence Spectroscopy
No full textDespite its simple crystal structure, layered boron nitride features a surprisingly complex variety of phonon-assisted luminescence peaks. We present a combined experimental and theoretical study on ultraviolet-light emission in hexagonal and rhombohedral bulk boron nitride crystals. Emission spectra of high-quality samples are measured via cathodoluminescence spectroscopy, displaying characteristic differences between the two polytypes. These differences are explained using a fully first-principles computational technique that takes into account radiative emission from "indirect," finite-momentum excitons via coupling to finite-momentum phonons. We show that the differences in peak positions, number of peaks, and relative intensities can be qualitatively and quantitatively explained, once a full integration over all relevant momenta of excitons and phonons is performed
Comparison of carrier dynamics in GaN quantum dots and GaN quantum wells embedded in low-Al-content AlGaN waveguides
No full textComparative analysis of the carrier dynamics of GaN quantum dot (QD) and GaN quantum well (QW) separated confinement heterostructures (SCHs) with low-Al-content AlGaN waveguide layers is reported. A redshift (blueshift) of QD (wetting layer) emission is found with respect to QW emission, as expected from the thickness hierarchy of these objects. The influence of nonradiative processes on QD emission in QD SCH is dramatically reduced compared to the case of QW SCH. It is concluded that GaN QDs in low-Al-content AlGaN matrix are robust localization centers and that the carrier dynamics is seriously affected by the built-in internal field effect. (c) 2006 American Institute of Physics.
Thick homoepitaxial (110)-oriented phosphorus-doped n-type diamond
No full textAbstract: The fabrication of n-type diamond is essential for the realization of electronic components for extreme environments. We report on the growth of a 66 mu m thick homoepitaxial phosphorus-doped diamond on a (110)-oriented diamond substrate, grown at a very high deposition rate of 33 mu m h(-1). A pristine diamond lattice is observed by high resolution transmission electron microscopy, which indicates the growth of high quality diamond. About 2.9 x 10(16) cm(-3) phosphorus atoms are electrically active as substitutional donors, which is 60% of all incorporated dopant atoms. These results indicate that P-doped (110)-oriented diamond films deposited at high growth rates are promising candidates for future use in high-power electronic applications. Published by AIP Publishing
Role of structural defects in the ultraviolet luminescence of multiwall boron nitride nanotubes
No full textBN nanotubes (BNNTs) are structurally similar to their carbon counterparts, though much less investigated. New synthesis methods have been recently reported, enabling the production of industrial quantities and stimulating the search of new applications for the BNNTs. In this paper, we investigate the luminescence of multiwall BNNTs. By performing cathodoluminescence experiments on single tubes at 10 K, we show that the tube luminescence is highly heterogeneous (i) from tube to tube and (ii) spatially along a single tube. By combining cathodoluminescence measurements with a nanometer excitation and transmission electron microscopy on the same tube, we correlate luminescence and structural features. We conclude that the near-band-edge luminescence of BNNTs (approximate to 5.4 eV) is related to the presence of extended structural defects, such as dislocations or ruptures in the wall stacking. (C) 2015 AIP Publishing LLC
Cathodoluminescence investigation of diffusion and exciton confinement in ZnO/ZnMgO and diamond 12C/ 13C heterostructures
No full textCe travail de thèse porte sur la diffusion des porteurs de charge en excès dans deux semiconducteurs à large bande interdite: l’alliage ZnMgO et le diamant 13C. Il est basé sur l’étude d’hétérostructures ZnMgO/ZnO/ZnMgO et 13C/12C/13C à puits de collecte ZnO ou 12C. Sur leurs sections transverses et avec la résolution nanométrique en excitation par cathodoluminescence (CL), nous avons étudié l’évolution de l’intensité de l’émission issue du puits en ZnO ou 12C en fonction de la distance entre l’impact de l’excitation et le puits. Cela nous a permis de mesurer directement les longueurs de diffusion effectives dans ZnMgO et le diamant.Dans ZnMgO, la valeur de 55 nm à 300 K, mesurée sur section transverse clivée, est proche de celle du matériau massif. Elle correspond à une diffusion mixte excitons/porteurs libres. Avec l’utilisation de lames minces érodées par faisceau d’ions, une diminution de a été observée jusqu’à 8 nm dans les parties les plus fines. Cet effet est attribué aux recombinaisons non radiatives de surface. Les lames minces apparaissent alors d’un grand intérêt pour améliorer la résolution spatiale des images CL.Dans le diamant, la diffusion excitonique à basse température montre une faible dépendance de avec l’énergie incidente des électrons. Cela indique que ≈ 15 µm à 20 K dans le diamant massif 13C. Une diminution de jusqu’à 3,3 µm à 118 K est observée en fonction de la température.Enfin, nous avons mis en évidence la formation de polyexcitons dans le diamant en augmentant la densité des paires électron-trou, soit par la puissance d’excitation, soit par le confinement spatial des excitons dans des puits de diamant 12C de faible épaisseurs.This work focuses on the determination of the carrier diffusion length in two wide bandgap semiconductors: the ternary alloy ZnMgO and diamond. This determination has been achieved by using of ZnMgO/ZnO/ZnMgO and 13C/12C/13C heterostructures containing ZnO or 12C collecting wells. Their transverse section was scanned by CL spectroscopy with a nanometer scale resolution in excitation. The effective excess carrier diffusion length is deduced from the evolution of the well emission intensity with the distance between the excitation impact and the well.In ZnMgO, the value at 300 K is 55 nm, obtained from a cleaved cross section. It is close to the bulk material diffusion and is attributed to a mixed diffusion of excitons/free carriers. A decrease of down to 8 nm is observed in the thinnest portions of cross sections shaped by focused ion beam (FIB). This effect is attributed to non-radiative surface recombinations. These thin slabs appear of great interest to enhance the spatial resolution of CL images.In diamond, the exciton diffusion at 20 K exhibits a slight dependence on the incident electron energy. This indicates that the exciton diffusion length is around 15 µm in 13C bulk diamond. The values decrease down to 3.3 µm at 118 K.Finally, we highlighted the formation of polyexcitons in diamond by increasing the electron-hole pairs density either by the excitation power, or by the spatial confinement of excitons in thin 12C wells
Growth and Marketing Strategy for a Health and Wellness Company
No full text[ABSTRACT ONLY; NO FULL TEXT] After several years of learning about business and of all the things necessary to run, manage, start, maintain and grow a business there is no better way to end the journey than with a growth and marketing plan for a company. This project required the team to recall practices and things we learned since beginning this program. It exposed us to all facets of this company and required us to do an in-depth analysis of the company and industry. We have conducted research and collected as much data that is relevant to our case. We have collected primary data in the form of surveys from both current clients of the company and potential future demographics. The analysis of all the data we have collected was the actual challenge because we had to sift through mountains of information in order to pull the most relevant and impactful information. We used the SWOT analysis as our main framework to develop the research and broke it down among us. Even after splitting all the work and completing the project it seemed as though there was still so much more to say and add. I focused on the opportunities and threats as well as developing recommendations to lessen the impact of the threats while taking advantage of the opportunities. I was able to use secondary data to substantiate my claims, as well as, develop some ideas that are unique to the company. We not only wanted to perform well for ourselves and our grades, but also wanted to deliver quality work to the client. Believing in our abilities and the final product we are delivering to our client is truly the biggest challenge because we want the client to succeed and we want our consultation to be of great value. The journey taken to complete this plan was fraught with complexities, but using our skills coupled with what we have learned over the years allowed us to navigate that difficult terrain and accomplish something that, at one time, seemed daunting and impossible. The Findings and recommendations from this project are proprietary to the client and shall remain confidential.California State University, Northridge. Department of Nazarian College Graduate Programs
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