BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:Basic Research and applied perspectives of chalcogenide phase-chan ge materials grown by molecular beam epitaxy DTSTART:20171211T131500 DTEND:20171211T141500 DTSTAMP:20260510T135106Z UID:172a84370c760346f70f0f883b241994524a9a77fd60be5eefdce558 CATEGORIES:Conferences - Seminars DESCRIPTION:Prof. Raffaella Calarco\, Paul-Drude-Institut für Festkörper elektronik\, Berlin Germany\nFor twenty years chalcogenide phase-change ma terials (PCMs) have found their major application in re-writable optical s torage media. Nowadays\, PCMs are employed also in microelectronics for no n-volatile electrical random access memories (PCRAM). The success of these materials is related to the rapid phase-change from the crystalline to th e amorphous state\, both exhibiting dissimilar optical contrast which is a lso accompanied by a huge difference in resistivity. Many different compou nds exhibit PCM properties\; however the most interesting\, from both a fu ndamental and practical perspective for PCRAM application are the alloys a long the GeTe-Sb2Te3 binary line.\nThe understanding of the switching proc ess in PCM\, dating back to the 1970s\, was based upon a picture in which an amorphous phase is generated by a rapid cooling of the melt and the cor responding crystalline phase is created by annealing the amorphous phase a bove the crystallization temperature. While this simple idea has a strong appeal\, the subtle nature of PCM bonding was shown to offer the interpret ation to the switching. In fact\, from the atomistic perspective the switc hing process has been suggested to be a reduction in the Ge coordination f rom octahedral (crystalline phase) to tetrahedral (amorphous phase) symmet ry\, accompanied by the breaking of the so called resonant bonds.\nOur gro up pioneered the growth of single and multi-layer chalcogenide material by molecular beam epitaxy (MBE). It has to be noted that industrial PCRAM sa mples are usually grown by sputtering\, a technique that does not allow fo r a perfect interface quality. MBE in contrast\, accomplishes this require ment and combines superior thickness control with ultrahigh purity and the possibility of using a variety of in-situ characterization tools. MBE the refore helps in elucidating the fundamental growth mechanisms of a commerc ially highly relevant material and establishing a material basis for innov ative devices\, beneficial from both academic and applied perspectives. In this respect\, we have recently enlightened the epitaxial rules that appl y to this class of materials1\,2\,3\,4\,5. Such understanding has inspired the optimization of the structural properties of chalcogenide materials u sed for the realization of PCRAM test cells6 and allowed detailed photoele ctron spectroscopy studies7 as well as the investigation of the metal insu lator transition8\,9.\nReferences:\n1 J.E. Boschker\, J. Momand\, V. Braga glia\, R. Wang\, K. Perumal\, A. Giussani\, B.J. Kooi\, H. Riechert\, and R. Calarco\, Nano Lett. 14\, 3534 (2014).\n2 R. Wang\, J.E. Boschker\, E. Bruyer\, D. Di Sante\, S. Picozzi\, K. Perumal\, A. Giussani\, H. Riechert \, and R. Calarco\, J. Phys. Chem. C 118\, 29724 (2014).\n3 E. Zallo\, S. Cecchi\, J.E. Boschker\, A.M. Mio\, F. Arciprete\, S. Privitera\, and R. C alarco\, Sci. Rep. 7\, 1466 (2017).\n4 R. Wang\, D. Campi\, M. Bernasconi\ , J. Momand\, B.J. Kooi\, M.A. Verheijen\, M. Wuttig\, and R. Calarco\, Sc i. Rep. 6\, 32895 (2016).\n5 R. Wang\, W. Zhang\, J. Momand\, I. Ronneberg er\, J.E. Boschker\, R. Mazzarello\, B.J. Kooi\, H. Riechert\, M. Wuttig\, and R. Calarco\, NPG Asia Mater. 9\, e396 (2017).\n6 J.E. Boschker\, M. B oniardi\, A. Redaelli\, H. Riechert\, and R. Calarco\, Appl. Phys. Lett. 1 06\, 23117 (2015).\n7 M. Liebmann\, C. Rinaldi\, D. Di Sante\, J. Kellner\ , C. Pauly\, R.N. Wang\, J.E. Boschker\, A. Giussani\, S. Bertoli\, M. Can toni\, L. Baldrati\, M. Asa\, I. Vobornik\, G. Panaccione\, D. Marchenko\, J. Sánchez-Barriga\, O. Rader\, R. Calarco\, S. Picozzi\, R. Bertacco\, and M. Morgenstern\, Adv. Mater. 28\, 560 (2016).\n8 V. Bragaglia\, F. Arc iprete\, W. Zhang\, A.M. Mio\, E. Zallo\, K. Perumal\, A. Giussani\, S. Ce cchi\, J.E. Boschker\, H. Riechert\, S. Privitera\, E. Rimini\, R. Mazzare llo\, and R. Calarco\, Sci. Rep. 6\, 23843 (2016).\n9 V. Bragaglia\, K. Ho lldack\, J.E. Boschker\, F. Arciprete\, E. Zallo\, T. Flissikowski\, and R . Calarco\, Sci. Rep. 6\, 28560 (2016).\n\nBio: Raffaella Calarco is Senio r Scientist at the Paul-Drude-Institut (PDI) in Berlin Germany. She receiv ed her Master’s degree in Physics in 1996 from the University of Rome To r Vergata. She holds a Ph.D. in Material Science in 2001 from the Universi ty of Rome La Sapienza. From 2000 to 2001 she worked as a Post-Doc at the University of Aachen (RWTH) Germany. From 2001 to 2010 she was with the Re search Center Jülich\, Germany\, at first in the Tenure-track excellence program and then as a Senior Research Scientist\, focusing on III-nitride nanowires. In 2010 she received the Habilitation in Physics from the RWTH Aachen and in 2012 from the Humboldt University in Berlin\, Germany. In 20 13 she obtained the Habilitation to full Professor in Italy. Since Septemb er 2010 she is with PDI\, her current research interests include on the on e hand epitaxy of III-nitride nanostructures and layers on the other hand epitaxial growth of phase-change materials for memory applications. Involv ed in National and International projects and European networks\, she coll aborates with several institutions. She is Coordinator of the EU Project 6 42574 of the Marie Skłodowska-Curie Actions (MSCA) Innovative Training Ne tworks (ITN) H2020. She has been serving as Work Package Leader in the EU- FP7 ICT Project PASTRY. She has been awarded with the Ovshinsky Lectureshi p Award 2017 for outstanding contribution to Ovonic Science and Technology and with the E/PCOS 2012 excellent presentation Award. Furthermore she pa rticipated to Helmholtz-Akademie für Führungskräfte and the “Tenure-t rack”- excellence program of the Forschungszentrum Jülich.  Since 2012 is member of the International scientific selection committee for proposa l of the Synchrotron Radiation Source BESSY II. She is author or coauthor of about 145 publications\, 59 invited talks\, 4 book chapters\, 5 invited review papers\, and 2 patents. She has about 3600 citations and her curre nt Hirsch index is 30 (on Google Scholar).\n  LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201 STATUS:CONFIRMED END:VEVENT END:VCALENDAR