¤ The scientific profile of the project leader
The project leader, Dr. Emil Mihai Pavelescu, is a senior researcher 1st grade (the highest rank in Romania) at the National Institute for Research and Development in Microtechnologies IMT- Bucharest since 2009 and an associate professsor at the Faculty of Exact Sciences and Engineering of Hyperion University since 2011. He has authored and co-authored over 75 publications in international and national peer-review journals and proceedings (all ISI ranked) gathering 628 citations (without selfcitations) with an h-index of 15.
After 6 months spent (under the aegis of a Romanian Governmental Fellowship earned followed a national contest) at the Microelectronics Research Group of IESL/FORTH (where he characterized by photoluminecence GaN-based materials – an imprtant technique for the current proposal), Greece, he has been for 5 years with the Optoelectronics Research Center (ORC) of Tampere University of Technology including an initial 1 year Marie Curie Fellowship at the ORC.
During this stay he has been intensively involved in 2 international (MONOPLA and FAST ACCESS) and several Finnish projects dealing with growth (molecular-beam epitaxy – the key technique for the current project proposal) and characterization of III-V semiconductors and devices, especially (dilute) nitride alloys. While at ORC, he successfully introduced and applied the strain compensation/mediation approach to engineer the highly strain of GaInNAs/GaAs quantum well heterostructures. The results were published in Applied Physics Letters (DOI: 10.1063/1.1470223) gathering over 60 citations, based on ISI Web of Science.
The experience accumulated on this topic wil be applied to BInGaN/GaN alloys. He was also the first in the world to emphasize the key role of selfannealing effect in optical activity of (dilute)nitride-containing devices and the subsequent publication on this finding in Applied Physics Letter (DOI: 10.1063/1.1601309) was very well appreciated and cited over 40 times. The effects of self annealing are very important and will be
taken into account in design and growth of the p-i-n GaN+/BInGaN/GaN- solar cells, when the p-type GaN top layer is usually grown at a much higher temperature around 720 oC after deposition of the BInGaN layer at temperatures around 520 oC, to avoid strong In desorption. In parallel with developing dilute-nitride heterostructures for light emitters, he started research activity on nitrogen incorporation into GaInNAs layers lattice matched to GaAs (Journal of Applied Physics; DOI:
10.1063/1.2112173, 20 citations) a research which constituted the preliminary grounds of the future solar cells currently developed in ORC.
The experience in developing (growing) dilute GaInNAs alloys lattice matched to GaAs will be used in this project for developing BInGaN alloys with low B content lattice matched to GaN. At ORC, he found that the optical activity of InGaNAs/GaAsQWs improves semnificantly if the structures are electron irradiated and subsequently thermall annealed (Pavelescu et al., Appl. Phys. Lett. DOI: 10.1063/1.1834997, 15 citations).
After the ORC research stage, he has also been for 3 years with the Technological Physics group of University of Kassel as a senior researcher where he led a research group on molecular-beam epitaxy of III-V quantum dots semiconductor compounds and heterostructures. At the same time, he was involved in implementation of the European project “Brighter” and was the key member of the Kassel University research team involved in European project “DeLight”. During the work within the “Brighter” project, he realized a quantum dot laser exhibiting the lowest wavelength dependence of its lasing wavelength with temperature without distributed feedback gratings or a Peltier cooler, which is still a worldwide record (DOI: 10.1088/0268-1242/23/8/085022).
After joining the IMT-Bucharest, he found, leading the current international project N- IBCell (Engineered group III-N-(As) alloys and low-dimensional heterostructures for high efficiency intermediate band solar cells) and the previously coordinated project (Development of advanced heterostructures containing III-N compound semiconductors used in high efficiency solar cells), that electron irradiation and subsequent thermal annealing also remarkably improves the optical quality of GaInNAs alloys lattice matched to GaAs not only that of the strained GaInNAs/GaAs QWs (Pavelescu et al. DOI: 10.1088/0268-1242/28/2/025020, DOI:
10.1016/j.jlumin.2012.12.008, DOI: 10.1016/j.jlumin.2014.05.042), as previously found in ORC.
This finding is very important, as this technology will be applied to our BInGaN/GaN alloys to improve their optical activity. Within the N-IBCell project, he also successfully developed a p-i-n GaAs+/InAs/Ga(In)NAs/GaAs- solar cell (Pavelescu et al., DOI: 10.1016/j.optmat.2015.12.035), key experience for developing the proposed p-i-n GaN/BInGaN/GaN solar cells. The last but not the least, within the same project, he managed very recently (unpublished yet to be submitted to
2016 MBE conference as late news) to incorporate a record (based on our knowledge) 7.7% of B into GaN by MBE, constituting the most powerful momentum for our target of growing BInGaN layers lattice matched to GaN with boron contents ≥10%.
The 18 peer-reviewed ISI-ranked journal articles (8 as a main author) published after getting the PhD without contribution of the PhD supervisor (Prof. Markus Pessa) and numerous citations (628) with a large h-index (15) of the project leader publications in ISI-ranked journal illustrates by themselves not only the independent research activity of the applicant but also its clear international visibility.
The outstanding scientific achievements of the project leader in the last 10 years, 2006 – present
1. Articles
1. E.-M. Pavelescu, V. Polojarvi, A. Schramm, A. Tukiainen, A. Aho, W.X. Zhang, J.Puustinen, J. Salmi, M. Guina, “Effects of insertion of strain-engineering Ga(In)NAs layers on optical properties of InAs/GaAs quantum dots for high-efficiency solar cells”, Optical Materials Vol. 52, pp. 177-180, 2016.
2. E.-M. Pavelescu, M. Dumitrescu, M. Guina, “Instability of structural defects generated by electron irradiation in GaInNAs quantum wells”, J. Luminescence, Vol.154, pp. 584-586,
2014.
3. E.-M. Pavelescu, R. Kudrawiec, M. Dumitrescu, “On photoluminescence and photoreflectance of 1-eV GaInNAs-on-GaAs epilayers”, J. Luminescence, Vol. 141, pp. 67-
70, 2013.
4. E-M. Pavelescu, R. Kudrawiec, N. Bălţăţeanu, S. Spȃnulescu, M. Dumitrescu, M. Guina, „Enhancement in photoluminescence from 1 eV GaInNAs epilayers subject to 7 MeV electron irradiation”, Semicond. Sci. Technol., Vol. 28, pp. 025020, 2013.
5. E.-M. Pavelescu, R. Kudrawiec, J. Puustinen, A. Tukiainen, M. Guina, “Effects of 7-MeV electron irradiation on photoluminescence from 1-eV GaInNAs-on-GaAs epilayers”, J. Luminescence, Vol. 136, pp. 347-50, 2013.
6. E.-M. Pavelescu, C Gilfert, P Weinmann, M Danila, A Dinescu, M. Kamp and J.-P.Reithmaier, “1100-nm InGaAs/(Al)GaAs quantum dot lasers for high power applications”, J. Phys. D.: Appl. Phys., Vol. 44, 145104, 2011.
7. C. Gilfert, E. M. Pavelescu, and J.P. Reithmaier, “Influence of the As2/As4 growth modes on the formation of quantum dot like InAs islands grown on InAlGaAs/InP (100)”, Appl. Phys. Lett., Vol. 96, 191903, 2010.
8. M. Syperek, P. Leszczyński, J. Misiewicz, E. M. Pavelescu, C. Gilfert, and J. P. Reithmaier, “Time-resolved photoluminescence spectroscopy of an InGaAs/GaAs quantum well-quantum dots tunnel injection structure“, Appl. Phys. Lett., Vol. 96, pp. 011901, 2010.
9. E.-M. Pavelescu, C. Gilfert, J. P. Reithmaier, A. Martín-Mínguez, I. Esquivias, “High- power tunnel-injection 1060-nm InGaAs-(Al)GaAs quantum-dot lasers”, IEEE Photon.
Tech. Lett, Vol. 21, pp. 999, 2009.
10. E. M. Pavelescu, J.P. Reithmaier, W. Kaiser, P. Weinmann, M. Kamp, A. Forchel, "Wavelength stabilized quantum dot lasers for high power applications", Phys. Stat. Sol. B, Vol. 246, pp. 872, 2009.
11. E-M Pavelescu, C Gilfert, J P Reithmaier, A Martín-Mínguez and I Esquivias, ‘GaInAs/(Al)GaAs quantum-dot lasers with high wavelength stability’ Semicond. Sci. Technol., Vol. 23, pp. 085022, 2008.
12. E.-M. Pavelescu, J. Slotte, V.D.S. Dhaka, K. Saarinen, S. Antohe, Gh. Cimpoca, and M. Pessa, ‘On the optical crystal properties of quantum-well GaIn(N)As/GaAs semiconductors grown by molecular-beam epitaxy’ J. Cryst. Growth, vol. 297, pp. 33-37, 2006.
13. J. Slotte, K. Saarinen, E.-M. Pavelescu, T. Hakkarainen, and M. Pessa, ‘Nitrogen related vacancies in GaAs based quantum well superlattices’, Appl. Phys. Lett., vol. 89, pp. 061903,
2006.
14. V. Dhaka, N. Tkachenko, H. Lemmetyinen, E.-M. Pavelescu, J. Konttinen, M. Pessa, K.Arstila, and J. Keinonen, ‘Room-temperature self-annealing of heavy-ion-irradiated InGaAs/GaAs quantum wells’ Electron. Lett., vol. 41, pp. 1304-1305, 2006.
2. Books/ chapters (including monographs) :
1. Engineered Quantum Dot Structures: Fabrication and Applications, Reithmaier, Johann Peter; Pavelescu, Emil-Mihai; Gilfert, Christian; et al., QUANTUM SENSING AND NANOPHOTONIC DEVICES VI Book Series: Proceedings of SPIE-The International Society for Optical Engineering Vol. 7222, 72220R, 2009. – review article
2. Emil-Mihai Pavelescu, “Research and Development of Dilute Nitride Semiconductors GaInNAs-on-GaAs”, TTY-PAINO, Tampere, 2004. ISBN 952-15-1235-0, ISSN 1459-2045. - book
3. Li, M. Pessa, T. Jouhti, C. S. Peng, and E.-M. Pavelescu, ‘GaInNAs quantum well lasers’, Encyclopedia of Nanoscience and Nanotechnology, vol. 3, pp. 719-730, 2004, ISBN: 1-58883-059-4. – book chapter
4. W. Li, J. Konttinen, T. Jouhti, C.S. Peng, E.-M. Pavelescu, M.Suominen, M. Pessa, “Extending the emission wavelength of GaInNAs/GaAs quantum well lasers beyond
1300 nm”, Advanced Nanomaterials and Nanodevice, Institute of Physics Publishing. IOP Publishing Ltd. 2003, pp. 251-260, ISBN: 0750309652, 2003. – review article
5. Pessa, M, Peng, CS, Jouhti, T, Pavelescu, EM, Li, W, Karirinne, S, Liu, H, Okhotnikov, O, “Long-wavelength nitride lasers on GaAs”, MICROELECTRONIC ENGINEERING Vol. 69 Issue: 2-4, pp. 195-207, 2003 – review article
3. Reseach projects
The project leader was involved in the following projects having as the main topic solar cells:
I. 2015-2017 Project Coordinator, national project: “Novel III-N-Bi semiconductor compounds for high efficiency solar cells” PN-II-RU-TE 2014, http://www.imt.ro/N-BiCell/
II. 2014-2017 Project Coordinator, international project (Norwegian University of Science and Technology as partner): “Engineered group III-N-(As) alloys and low-dimensional heterostructures for high efficiency intermediate band solar cells”, EEA-RO 2009-2014 Financial Mechanism, http://www.imt.ro/N-iBCell/index_en.php. Papers published so far:
1. E.-M. Pavelescu et al., Effects of insertion of strain-engineering Ga(In)NAs layers on optical properties of InAs/GaAs quantum dots for high-efficiency solar cells, OPTICAL MATERIALS Volume: 52 Pages: 177-180 Published: FEB 2016
2. V. Polojarvi, E.-M. Pavelescu et al., Optical properties and thermionic emission in solar cells with InAs quantum dots embedded within GaNAs and GaInNAs, SCRIPTA MATERIALIA Volume: 108 Pages: 122-125 Published: NOV 2015
3. E.-M. Pavelescu et al., Instability of structural defects generated by electron irradiation in GaInNAs quantum wells, JOURNAL OF LUMINESCENCE Volume: 154 Pages: 584-586 Published: OCT 2014
III. 2010-2012 Principal Investigator (PI), national project: “Development of advanced heterostructures containing III-N compound semiconductors used in high efficiency solar cells”, POSDRU/89/1.5/63700
1. E.-M. Pavelescu et al., On photoluminescence and photoreflectance of 1-eV GaInNAs-on-GaAs epilayers, JOURNAL OF LUMINESCENCE Volume: 141 Pages: 67-70 Published: SEP 2013
2. E.-M. Pavelescu et al., Effects of 7-MeV electron irradiation on photoluminescence from 1-eV GaInNAs-on-GaAs epilayers, JOURNAL OF LUMINESCENCE Volume: 136 Pages: 347-350
Published: APR 2013
3. Pavelescu et al., Enhancement in photoluminescence from 1 eV GaInNAs epilayers subject to 7 MeV electron irradiation, SEMICONDUCTOR SCIENCE AND TECHNOLOGY Volume: 28, Issue: 2 Article Number: 025020 Published: FEB 2013
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