BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Memento EPFL// BEGIN:VEVENT SUMMARY:IMX Seminar Series - Computational Discovery and Experimental Vali dation of Rutile GeO2 and GeSnO2 Alloys: A New Family of Ultra-Wide-Band-G ap Semiconductors for Power Electronics DTSTART:20240909T131500 DTEND:20240909T141500 DTSTAMP:20260525T080620Z UID:75affde3733b57976b23be11bed2560dfbc58d7b9ca8b75ac0980daa CATEGORIES:Conferences - Seminars DESCRIPTION:Prof. Manos Kioupakis\, University of Michigan\, USA\nSemicond ucting materials play a crucial role in modern society\, from information technology and optical communications to renewable energy generation and v ehicle electrification. In particular\, ultra-wide-band-gap (UWBG) semicon ductors\, i.e.\, semiconductors with band gaps wider than the 3.5 eV value of GaN\, are promising for higher efficiency\, reduced size\, and lower c ost in high-power electronics applications. For example\, materials such a s diamond\, cubic BN\, β-Ga2O3\, and AlGaN promise higher conversion effi ciency and orders-of-magnitude improvements in power density compared to c urrent technologies (Si\, SiC\, and GaN). However\, none of the above UWBG materials offers all the desired properties needed for high-performance e lectronics and\, despite decades of research\, very few alternative UWBG s emiconductors have been realized to date. There is therefore a pressing ne ed to develop synergistic methods that combine predictive theory with expe rimental synthesis and validation in order to discover and design new UWBG semiconductors that can surpass the limitations of current technologies.\ nIn recent years\, our team has advanced the development of rutile GeO2 an d its alloys with SnO2 as a novel family of UWBG semiconductors that can s urpass the state of the art in power electronics. Our predictive atomistic calculations demonstrate that these alloys exhibit superior fundamental p roperties that overcome the limitations of current materials. Their band g aps span from 3.6 eV for SnO2 to 4.68 eV for rutile GeO2 [1]. They are pre dicted to exhibit ambipolar dopability\, with SbGe\, AsGe\, TaGe\, Hi\, an d FO acting as shallow donors\, while AlGe and GaGe acting as acceptors [2 ]. The predicted carrier mobilities are high [3]\, while the relatively li ght carrier effective masses prevent the formation of self-trapped polaron s. The predicted thermal conductivity is also high and surpasses β-Ga2O3\ , a prediction that we verified experimentally in unoptimized polycrystall ine bulk samples [4]. Overall\, we find that the predicted Baliga figure o f merit of rutile GeO2 (i.e.\, a measure of the performance of materials i n power electronics)\, modified to account for donor ionization\, surpasse s all known semiconductors\, demonstrating its unique potential for energy -efficient power electronics [5].\nExperimentally\, we demonstrate the syn thesis of single-crystalline GeO2-based thin films and substrates\, which are prerequisites for epitaxial devices. Using suboxide molecular-beam epi taxy (MBE)\, we demonstrate the stability of GeSnO2 alloy thin films over their entire composition range [6]\, while the development and epitaxy on single-crystalline rutile GeO2 substrates enables the epitaxy of single-cr ystalline thin films [7]. Overall\, our work demonstrates the unique promi se of rutile GeO2-based materials for advancing the state of the art in po wer electronic devices.\n\n[1] J. Appl. Phys. 126\, 085703 (2019)\n[2] App l. Phys. Lett. 114\, 102104 (2019)\n[3] Appl. Phys. Lett. 117\, 182104 (20 20)\n[4] Appl. Phys. Lett. 117\, 102106 (2020)\n[5] Appl. Phys. Lett. 118\ , 260501 (2021)\n[6] Appl. Phys. Lett. 117\, 072105 (2020)\n[7] J. Vac. Sc i. Technol. A 40\, 050401 (2022)\n\nBio: Emmanouil (Manos) Kioupakis is a Professor of Materials Science and Engineering and the Karl F. and Patrici a J. Betz Family Faculty Scholar at the University of Michigan. He obtaine d his PhD in Physics at the University of California\, Berkeley\, and his undergraduate degree in Physics at the University of Crete. He also held a postdoctoral appointment in Materials at the University of California\, S anta Barbara.\nProf. Kioupakis’ research group focuses on developing and applying predictive materials-modeling methods to explain and predict the synthesis and functionalities of new semiconductor materials for electron ics\, optoelectronics\, and energy applications. Highlights of his work in clude pioneering calculations of phonon-mediated quantum phenomena in mate rials\, such as optical absorption in silicon and non-radiative recombinat ion in LEDs\, as well as uncovering fundamental insights on the structure- property relationships of modern nitride and oxide semiconductors. He has supervised the PhD research of 21 students of diverse backgrounds\, who pu rsue independent careers in academia\, national laboratories\, and the mic roelectronics industry. The courses he teaches at the University of Michig an on the physics and thermodynamics of materials focus on incorporating a ctive-learning techniques into the large-classroom setting. Among numerous positive educational outcomes\, these methods have also been demonstrated to increase the retention of female students in Engineering. Prof. Kioupa kis has received the U.S. National Science Foundation CAREER Award\, the J on R. and Beverly S. Holt Award for Excellence in Teaching\, and the Engin eering Class of 1938 Award\, the highest honor to early-career faculty in Engineering at the University of Michigan.\nDuring the academic year 2024- 25\, Prof. Kioupakis is on sabbatical leave from the University of Michiga n and is hosted as a Visiting Professor by IMX and IEM in STI at EPFL. Pro f. Kioupakis will be hosted by Prof. Nicola Marzari at the Laboratory of t heory and simulation of materials (THEOS) and the NCCR MARVEL\, and by Pro f. Elison Matioli at the power and wide-band-gab electronics research labo ratory (POWERLAB). During his stay at EPFL\, Prof. Kioupakis aims to engag e on a broad range of collaborative research activities on the science and engineering of semiconducting materials and devices\, and he is looking f orward to fruitful discussions and networking with the EPFL community.\n  LOCATION:MXF 1 https://plan.epfl.ch/?room==MXF%201 STATUS:CONFIRMED END:VEVENT END:VCALENDAR