@article{RudnoRudzińskiSyperekAndrezejewskietal.2017, author = {Rudno-Rudziński, W. and Syperek, M. and Andrezejewski, J. and Maryński, A. and Misiewicz, J. and Somers, A. and H{\"o}fling, S. and Reithmaier, J. P. and Sęk, G.}, title = {Carrier delocalization in InAs/InGaAlAs/InP quantum-dash-based tunnel injection system for 1.55 μm emission}, series = {AIP Advances}, volume = {7}, journal = {AIP Advances}, number = {1}, doi = {10.1063/1.4975634}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-181787}, year = {2017}, abstract = {We have investigated optical properties of hybrid two-dimensional-zero-dimensional (2D-0D) tunnel structures containing strongly elongated InAs/InP(001) quantum dots (called quantum dashes), emitting at 1.55 μm. These quantum dashes (QDashes) are separated by a 2.3 nm-width barrier from an InGaAs quantum well (QW), lattice matched to InP. We have tailored quantum-mechanical coupling between the states confined in QDashes and a QW by changing the QW thickness. By combining modulation spectroscopy and photoluminescence excitation, we have determined the energies of all relevant optical transitions in the system and proven the carrier transfer from the QW to the QDashes, which is the fundamental requirement for the tunnel injection scheme. A transformation between 0D and mixed-type 2D-0D character of an electron and a hole confinement in the ground state of the hybrid system have been probed by time-resolved photoluminescence that revealed considerable changes in PL decay time with the QW width changes. The experimental discoveries have been explained by band structure calculations in the framework of the eight-band k·p model showing that they are driven by delocalization of the lowest energy hole state. The hole delocalization process from the 0D QDash confinement is unfavorable for optical devices based on such tunnel injection structures.}, language = {en} } @article{RyczkoMisiewiczHoflingetal.2017, author = {Ryczko, K. and Misiewicz, J. and Hofling, S. and Kamp, M. and Sęk, G.}, title = {Optimizing the active region of interband cascade lasers for passive mode-locking}, series = {AIP Advances}, volume = {7}, journal = {AIP Advances}, number = {1}, doi = {10.1063/1.4973937}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-181790}, year = {2017}, abstract = {The work proposes possible designs of active regions for a mode-locked interband cascade laser emitting in the mid infrared. For that purpose we investigated the electronic structure properties of respectively modified GaSb-based type II W-shaped quantum wells, including the effect of external bias in order to simultaneously fulfil the requirements for both the absorber as well as the gain sections of a device. The results show that introducing multiple InAs layers in type II InAs/GaInSb quantum wells or introducing a tensely-strained GaAsSb layer into "W-shaped" type II QWs offers significant difference in optical transitions' oscillator strengths (characteristic lifetimes) of the two oppositely polarized parts of such a laser, being promising for utilization in mode-locked devices.}, language = {en} } @phdthesis{Miller2024, author = {Miller, Kirill}, title = {Untersuchung von Nanostrukturen basierend auf LaAlO\(_3\)/SrTiO\(_3\) f{\"u}r Anwendungen in nicht von-Neumann-Rechnerarchitekturen}, doi = {10.25972/OPUS-35472}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-354724}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {Die Dissertation besch{\"a}ftigt sich mit der Analyse von oxidischen Nanostrukturen. Die Grundlage der Bauelemente stellt dabei die LaAlO3/SrTiO3-Heterostruktur dar. Hierbei entsteht an der Grenzfl{\"a}che beider {\"U}bergangsmetalloxide ein quasi zweidimensionales Elektronengas, welches wiederum eine F{\"u}lle von beachtlichen Eigenschaften und Charakteristika zeigt. Mithilfe lithographischer Verfahren wurden zwei unterschiedliche Bauelemente verwirklicht. Dabei handelt es sich einerseits um einen planaren Nanodraht mit lateralen Gates, welcher auf der Probenoberfl{\"a}che prozessiert wurde und eine bemerkenswerte Trialit{\"a}t aufweist. Dieses Bauelement kann unter anderem als ein herk{\"o}mmlicher Feldeffekttransistor agieren, wobei der Ladungstransport durch die lateral angelegte Spannung manipuliert wird. Zus{\"a}tzlich konnten auch Speichereigenschaften beobachtet werden, sodass das gesamte Bauelement als ein sogenannter Memristor fungieren kann. In diesem Fall h{\"a}ngt der Ladungstransport von der Elektronenakkumulation auf den lateralen potentialfreien Gates ab. Die Memristanz des Nanodrahts l{\"a}sst sich unter anderem durch Lichtleistungen im Nanowattbereich und mithilfe von kurzen Spannungspulsen ver{\"a}ndern. Dar{\"u}ber hinaus kann die Elektronenakkumulation auch in Form einer memkapazitiven Charakteristik beobachtet werden. Neben dem Nanodraht wurde auch eine Kreuzstruktur, die eine erg{\"a}nzende ferromagnetischen Elektrode beinhaltet, realisiert. Mit diesem neuartigen Bauteil wird die Umwandlung zwischen Spin- und Ladungsstr{\"o}men innerhalb der nanoskaligen Struktur untersucht. Hierbei wird die starke Spin-Bahn-Kopplung im quasi zweidimensionalen Elektronengas ausgenutzt.}, subject = {Memristor}, language = {de} } @article{OPUS4-22774, title = {Characterisation of the Hamamatsu photomultipliers for the KM3NeT Neutrino Telescope}, series = {Journal of Instrumentation}, volume = {13}, journal = {Journal of Instrumentation}, organization = {The KM3NeT collaboration}, doi = {10.1088/1748-0221/13/05/P05035}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227744}, pages = {1-14}, year = {2018}, abstract = {The Hamamatsu R12199-023-inch photomultiplier tube is the photodetector chosen for the first phase of the KM3NeT neutrino telescope. About 7000 photomultipliers have been characterised for dark count rate, timing spread and spurious pulses. The quantum efficiency, the gain and the peak-to-valley ratio have also been measured for a sub-sample in order to determine parameter values needed as input to numerical simulations of the detector.}, language = {en} } @phdthesis{Bayer2024, author = {Bayer, Florian}, title = {Investigating electromagnetic properties of topological surface states in mercury telluride}, doi = {10.25972/OPUS-35212}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-352127}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2024}, abstract = {This doctoral thesis investigates magneto-optical properties of mercury telluride layers grown tensile strained on cadmium telluride substrates. Here, layer thicknesses start above the usual quantum well thickness of about 20 nm and have a upper boundary around 100 nm due to lattice relaxation effects. This kind of layer system has been attributed to the material class of three-dimensional topological insulators in numerous publications. This class stands out due to intrinsic boundary states which cross the energetic band gap of the layer's bulk. In order to investigate the band structure properties in a narrow region around the Fermi edge, including possible boundary states, the method of highly precise time-domain Terahertz polarimetry is used. In the beginning, the state of the art of Teraherz technology at the start of this project is discussed, moving on to a detailed description and characterization of the self-built measurement setup. Typical standard deviation of a polarization rotation or ellipticity measurement are on the order of 10 to 100 millidegrees, according to the transmission strength through investigated samples. A range of polarization spectra, depending on external magnetic fields up to 10 Tesla, can be extracted from the time-domain signal via Fourier transformation. The identification of the actual band structure is done by modeling possible band structures by means of the envelope function approximation within the framework of the k·p method. First the bands are calculated based on well-established model parameters and from them the possible optical transitions and expected ellipticity spectra, all depending on external magnetic fields and the layer's charge carrier concentration. By comparing expected with measured spectra, the validity of k·p models with varying depths of detail is analyzed throughout this thesis. The rich information encoded in the ellipitcity spectra delivers key information for the attribution of single optical transitions, which are not part of pure absorption spectroscopy. For example, the sign of the ellipticity signals is linked to the mix of Landau levels which contribute to an optical transition, which shows direct evidence for bulk inversion asymmetry effects in the measured spectra. Throughout the thesis, the results are compared repeatedly with existing publications on the topic. It is shown that the models used there are often insufficient or, in worst case, plainly incorrect. Wherever meaningful and possible without greater detours, the differences to the conclusions that can be drawn from the k·p model are discussed. The analysis ends with a detailed look on remaining differences between model and measurement. It contains the quality of model parameters as well as different approaches to integrate electrostatic potentials that exist in the structures into the model. An outlook on possible future developments of the mercury cadmium telluride layer systems, as well as the application of the methods shown here onto further research questions concludes the thesis.}, subject = {Quecksilbertellurid}, language = {en} } @article{LiShanRupprechtetal.2022, author = {Li, Donghai and Shan, Hangyong and Rupprecht, Christoph and Knopf, Heiko and Watanabe, Kenji and Taniguchi, Takashi and Qin, Ying and Tongay, Sefaattin and Nuß, Matthias and Schr{\"o}der, Sven and Eilenberger, Falk and H{\"o}fling, Sven and Schneider, Christian and Brixner, Tobias}, title = {Hybridized exciton-photon-phonon states in a transition-metal-dichalcogenide van-der-Waals heterostructure microcavity}, series = {Physical Review Letters}, journal = {Physical Review Letters}, edition = {accepted version}, issn = {1079-7114}, doi = {10.1103/PhysRevLett.128.087401}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-351303}, year = {2022}, abstract = {Excitons in atomically thin transition-metal dichalcogenides (TMDs) have been established as an attractive platform to explore polaritonic physics, owing to their enormous binding energies and giant oscillator strength. Basic spectral features of exciton polaritons in TMD microcavities, thus far, were conventionally explained via two-coupled-oscillator models. This ignores, however, the impact of phonons on the polariton energy structure. Here we establish and quantify the threefold coupling between excitons, cavity photons, and phonons. For this purpose, we employ energy-momentum-resolved photoluminescence and spatially resolved coherent two-dimensional spectroscopy to investigate the spectral properties of a high-quality-factor microcavity with an embedded WSe\(_2\) van-der-Waals heterostructure at room temperature. Our approach reveals a rich multi-branch structure which thus far has not been captured in previous experiments. Simulation of the data reveals hybridized exciton-photon-phonon states, providing new physical insight into the exciton polariton system based on layered TMDs.}, language = {en} } @article{OPUS4-22694, title = {FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2}, series = {European Physical Journal - Special Topics}, volume = {228}, journal = {European Physical Journal - Special Topics}, number = {2}, organization = {The FCC Collaboration}, doi = {10.1140/epjst/e2019-900045-4}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226947}, pages = {261-623}, year = {2019}, abstract = {In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today's technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics.}, language = {en} } @article{OPUS4-22693, title = {FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1}, series = {European Physical Journal C}, volume = {79}, journal = {European Physical Journal C}, number = {474}, organization = {The FCC Collaboration}, doi = {10.1140/epjc/s10052-019-6904-3}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226938}, pages = {1-161}, year = {2019}, abstract = {We review the physics opportunities of the Future Circular Collider, covering its e(+)e(-), pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics.}, language = {en} } @article{OPUS4-22692, title = {HE-LHC: The High-Energy Large Hadron Collider : Future Circular Collider Conceptual Design Report Volume 4}, series = {European Physical Journal - Special Topics}, volume = {228}, journal = {European Physical Journal - Special Topics}, number = {5}, organization = {The FCC Collaboration}, doi = {10.1140/epjst/e2019-900088-6}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226928}, pages = {1109-1382}, year = {2019}, abstract = {In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.}, language = {en} } @article{OPUS4-22691, title = {FCC-hh: The Hadron Collider: Future Circular Collider Conceptual Design Report Volume 3}, series = {European Physical Journal - Special Topics}, volume = {228}, journal = {European Physical Journal - Special Topics}, organization = {The FCC Collaboration}, doi = {10.1140/epjst/e2019-900087-0}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226917}, pages = {755-1107}, year = {2019}, abstract = {In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100TeV. Its unprecedented centre of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.}, language = {en} }