Semiconductor Nanostructures “Lendület” Research Group

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Introduction

Welcome to the Adam Gali group at Wigner Research Centre for Physics Our group’s research focuses on theoretical and experimental characterization of point defects in semiconductors and semiconductor nanostructures. We are developing and implementing new techniques for introducing dopants and defects in semiconductor (nano)structures, and studying their properties by experimental and theoretical spectroscopy tools.

We are looking for an experienced and ambitious researcher with a background in optically detected magnetic resonance (ODMR) techniques to study solid state qubits. This is a Postdoc job that can be turned to tenure track position for qualified researchers. Email your CV to Adam Gali!


We combine heat combustion, ion or neutron irradiation, colloid chemistry and related techniques to fabricate semiconductor nanostructures. Our focus is on silicon carbide to realize ultimate in vivo bioimaging agents. We are active in the field of computational materials science and has a large experience in using density functional theory (DFT) based methods in solids and nanostructures. The group leader started to apply advanced hybrid density functional theory methods on defects in bulk and nanostructured semiconductors already from 2002. From 2005 the GW method was also applied. Advanced time-dependent DFT (TDDFT) has been employed to determine the absorption spectrum of nanoclusters since 2008. These theories were utilized directly to defect engineering in bulk semiconductors and in their oxide interface, biomarkers, solid state quantum bits and spintronics, solar cells and related topics.


Projects

Publications: https://vm.mtmt.hu/search/slist.php?inited=1&co_on=&ty_on=1&la_on=&LanguageID=&abs_on=&sp_on=&st_on=&url_on=1&cite_type=2&orderby=3D1a&Scientific=1&Independent=&top10=&lang=1&location=mtmt&debug=&stn=1&AuthorID=10002866&DocumentID=&tipus=&besorolas=&jelleg=1Mtmt Publications Scholar.pngScholar Publications Scopus.pngScopus

Facilities & Support

People

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Group meeting in 2014 December
Group leader
Adam Gali
Postdoc fellows
Zoltán Bodrog
Dávid Beke
Viktor Ivády
Graduate students
Gyula Károlyházy
Bálint Somogyi
Gergő Thiering
Péter Udvarhelyi
András Csóré
Undergraduate students
Áron Dániel Major
Fanni Oláh
Balázs Juhász
Dániel Unyi
Ádám Pataki
Laboratory Assistants
Péter Rózsa
István Balogh

Highlights

2017 PRX.png

Our ab initio simulations determined the magneto-optical properties of the neutral divacancy in silicon carbide that contributed to understanding its qubit operation carried out by Prof. David D. Awschalom group.

Phys. Rev. X 7, 021046 (2017). DOI:10.1103/PhysRevX.7.021046


Nanoletters2017.png

Our ab initio study identified the nitrogen terminated (111) diamond surface to host shallow nitrogen-vacancy centers for quantum sensing. In cooperation with Alex Retzker we showed, that special quantum simulations can be carried out with the nitrogen nuclear spins in this system

Nano Letters 17 (4), pp 2294-2298. (2017) DOI:10.1021/acs.nanolett.6b05023


Adamant cover.png

We investigated the electron-phonon coupling in small diamond cages called diamondoids. These quantum systems are mostly modelled within the Born-Oppenheimer approximations, where the coupling between the electrons and vibration modes is not fully taken into account. In our study we shown that the severe electron-phonon coupling is a key point to properly describe the overall lineshape of the experimental photoemission spectrum. Our method goes beyond the typical Born-Oppenheimer approximation, where the electrons are pure electron-like quasi-particles. In our model, we deduced a link between the many-body perturbation approach of the electron-phonon coupling and the well-known Jahn-Teller effect.

Nature Communications 7: 11327. (2016). DOI:10.1038/ncomms11327



SiVHn.png

The chemical vapor deposition of diamond is known to introduce complexes of silicon, vacancy, and hydrogen. We theoretically examined several such complexes, some of which have already been observed, others which could potentially form. Using hybrid density functional theory for the treatment of highly correlated orbitals, many measurable quantities are calculated. The SiV2H(-) negatively charged defect is found to be a promising candidate for a long lived solid state quantum memory. The study is highlighted as Editor's suggestion in PRB.

Phys. Rev. B 92 165203 (2015). DOI:10.1103/PhysRevB.92.165203



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In collaboration with German (Jörg Wrachtrup group at Stuttgart University) and Swedish (Erik Janzén group at Linköping University) researchers, we report the characterization of photoluminescence and optical spin polarization from single silicon vacancies in ​SiC, and demonstrate that single spins can be addressed at room temperature. We show coherent control of a single defect spin and find long spin coherence times under ambient conditions. Our study provides evidence that ​SiC is a promising system for atomic-scale spintronics and quantum technology. Our study is highlighted in a News and Views article from Nature Materials.

Nature Materials 14 164-168 (2015). DOI:10.1038/nmat4145


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