Étude tracéologique de la perforation. Application aux perles gravettiennes de l’abri Pataud, du Blot, des Peyrugues

Cet article a pour but l’étude des modes de perforation des perles préhistoriques par la détermination de différents paramètres, la vérification de la validité de ces différents paramètres par l’expérimentation, les analyses et comparaisons entre les perles expérimentales et les perles préhistoriques par les examens non destructifs au Microscope Electronique à Balayage (MEB) et au micro-rugosimètre.The objective of this article is the perforation process of the prehistorically beads by the determination of the different parameters, the verification of the validity of different parameters by experimentation, the analyses and comparisons between the experimental beads and prehistorically beads by the investigation of nondestructive technique with Scanning Electronic Microscope (SEM) and microtopography

Experimental evidence of hot carriers solar cell operation in multi-quantum wells heterostructures

International audienceWe investigated a semiconductor heterostructure based on InGaAsP multi quantum wells (QWs) using optical characterizations and demonstrate its potential to work as a hot carrier cell absorber. By analyzing photoluminescence spectra, the quasi Fermi level splitting Dl and the carrier temperature are quantitatively measured as a function of the excitation power. Moreover, both thermodynamics values are measured at the QWs and the barrier emission energy. High values of Dl are found for both transition, and high carrier temperature values in the QWs. Remarkably, the quasi Fermi level splitting measured at the barrier energy exceeds the absorption threshold of the QWs. This indicates a working condition beyond the classical Shockley-Queisser limit

Hot Carrier Solar Cell: From Simulation to Devices

International audienceSingle junction III-V heterostructures based devices could overtake the Shockley-Queisser limit if thermalisation of photogenerated carriers can be strongly limited as in the hot carrier solar cell concept. Previous modelling and experiments have shown the interest of Multiple Quantum Wells heterostructures in the antimonide system and the importance of very thin structures. In this paper we report new data on the thermalisation rates in antimonide and phosphide heterostructures measured at ambient temperature. For the first time electrical control of hot carrier population is performed on hot carrier heterostructures device

Reply to the Comment of Y. Apertet on Optical Imaging of Light-Induced Thermopower in Semiconductors

International audienceIn a Comment on a previously published article in this Journal [Phys. Rev. Applied 5, 024005 (2016)] 1 , Apertet states that the definition of the thermopower given in that article seems erroneous due to a confusion between the different physical quantities needed to derive this parameter. We believe some definitions need to be clarified in order to avoid confusions. We here intend to answer the questions of Apertet by detailing the method and by focusing on the definition of the quantities we optically measured

Gérard Lyon-Caen

International audience(1919 - 2004

InP/InGaAsP Heterostructures for Hot Carrier Solar Cells (HCSC)

International audienceWe investigated a semiconductor heterostructure based on InGaAsP multi quantum wells using optical and electrical characterizations. The optical analysis allows us to probe the potential of such a structure in the scope of hot carrier solar cell device. Using different photoluminescence techniques, the quasi Fermi level splitting Δμ is estimated as a function of the excitation power. High value of Δμ is found as well as high carrier temperature. These results are compared to electrical measurements

Accurate measurement of temperature and electrochemical potential of InGaAsPlInP heterostructures: a first indication of hot carriers solar cell operation

International audienceWe investigated a semiconductor heterostructure based on InGaAsP multi quantum wells using optical and electrical characterizations. The optical analysis allows us to probe the potential of such a structure in the scope of hot carrier solar cell device. Using different photoluminescence techniques, the quasi Fermi level splitting Aft and the carrier temperature is estimated as a function of the excitation power. Both values are measured at the quantum wells and at the barrier emission energy. High values of Aft is found as well as high carrier temperature showing the capability of this structure to work as Hot Carrier Solar cell absorber. Aft measured in the barrier energy region exceeds the minimum absorption threshold. This fact evidences the potential quantum wells structure to overcome the Schockley Queisser limi

Characterization of InP/InGaAsP-multi-quantum-wells heterostructures for high efficiency solar energy conversion

International audienceWe investigated a semiconductor heterostructure based on InGaAsP multi quantum wells using optical and electrical characterizations. The optical analysis allows us to probe the potential of such a structure in the scope of hot carrier solar cell device. Using different photoluminescence techniques, the quasi Fermi level splitting Δμ is estimated as a function of the excitation power. High value of Δμ is found as well as high carrier temperature. These results are compared to electrical measurement

European integration and the variety of languages

International audienceWhile formal EU law acknowledges the equality of the 24 languages of the Member States, practice has sanctioned the blatant hegemony of the English language over the years, and the United Kingdom has now decided to leave the European Union. Most social scientists do not care about this situation. As members of a trans-European elite, they privilege the certainties of a standardised European English over the strict demands of science and truth that need pluri-lingualism. But there is more to pluri-lingualism than being an indispensable vector to rigorous social science. Language is also indispensable for politics and, as politics is now made in English in the European Union, non-speakers of English now face exclusion from full participation in politics. Contrary to received wisdom, this concerns the majority of European citizens. One key obstacle to the modification of language practices across the Union lies in the structural features of EU law itself, with regard to its very conception of language as a discriminating instrument

Hot Carrier Solar Cells: Controlling Thermalization in Ultrathin Devices

International audienc