@article{WyborskiPodemskiWrońskietal.2022,
  author    = {Wyborski, Paweł and Podemski, Paweł and Wroński, Piotr Andrzej and Jabeen, Fauzia and H{\"o}fling, Sven and Sęk, Grzegorz},
  title     = {Electronic and optical properties of InAs QDs grown by MBE on InGaAs metamorphic buffer},
  series = {Materials},
  volume    = {15},
  journal   = {Materials},
  number    = {3},
  issn      = {1996-1944},
  doi       = {10.3390/ma15031071},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-297037},
  year      = {2022},
  abstract  = {We present the optical characterization of GaAs-based InAs quantum dots (QDs) grown by molecular beam epitaxy on a digitally alloyed InGaAs metamorphic buffer layer (MBL) with gradual composition ensuring a redshift of the QD emission up to the second telecom window. Based on the photoluminescence (PL) measurements and numerical calculations, we analyzed the factors influencing the energies of optical transitions in QDs, among which the QD height seems to be dominating. In addition, polarization anisotropy of the QD emission was observed, which is a fingerprint of significant valence states mixing enhanced by the QD confinement potential asymmetry, driven by the decreased strain with increasing In content in the MBL. The barrier-related transitions were probed by photoreflectance, which combined with photoluminescence data and the PL temperature dependence, allowed for the determination of the carrier activation energies and the main channels of carrier loss, identified as the carrier escape to the MBL barrier. Eventually, the zero-dimensional character of the emission was confirmed by detecting the photoluminescence from single QDs with identified features of the confined neutral exciton and biexciton complexes via the excitation power and polarization dependences.},
  language  = {en}
}
@article{PfenningKruegerJabeenetal.2022,
  author    = {Pfenning, Andreas and Kr{\"u}ger, Sebastian and Jabeen, Fauzia and Worschech, Lukas and Hartmann, Fabian and H{\"o}fling, Sven},
  title     = {Single-photon counting with semiconductor resonant tunneling devices},
  series = {Nanomaterials},
  volume    = {12},
  journal   = {Nanomaterials},
  number    = {14},
  issn      = {2079-4991},
  doi       = {10.3390/nano12142358},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-281922},
  year      = {2022},
  abstract  = {Optical quantum information science and technologies require the capability to generate, control, and detect single or multiple quanta of light. The need to detect individual photons has motivated the development of a variety of novel and refined single-photon detectors (SPDs) with enhanced detector performance. Superconducting nanowire single-photon detectors (SNSPDs) and single-photon avalanche diodes (SPADs) are the top-performer in this field, but alternative promising and innovative devices are emerging. In this review article, we discuss the current state-of-the-art of one such alternative device capable of single-photon counting: the resonant tunneling diode (RTD) single-photon detector. Due to their peculiar photodetection mechanism and current-voltage characteristic with a region of negative differential conductance, RTD single-photon detectors provide, theoretically, several advantages over conventional SPDs, such as an inherently deadtime-free photon-number resolution at elevated temperatures, while offering low dark counts, a low timing jitter, and multiple photon detection modes. This review article brings together our previous studies and current experimental results. We focus on the current limitations of RTD-SPDs and provide detailed design and parameter variations to be potentially employed in next-generation RTD-SPD to improve the figure of merits of these alternative single-photon counting devices. The single-photon detection capability of RTDs without quantum dots is shown.},
  language  = {en}
}
@article{RothmayrGuarinCastroHartmannetal.2022,
  author    = {Rothmayr, Florian and Guarin Castro, Edgar David and Hartmann, Fabian and Knebl, Georg and Schade, Anne and H{\"o}fling, Sven and Koeth, Johannes and Pfenning, Andreas and Worschech, Lukas and Lopez-Richard, Victor},
  title     = {Resonant tunneling diodes: mid-infrared sensing at room temperature},
  series = {Nanomaterials},
  volume    = {12},
  journal   = {Nanomaterials},
  number    = {6},
  issn      = {2079-4991},
  doi       = {10.3390/nano12061024},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-267152},
  year      = {2022},
  abstract  = {Resonant tunneling diode photodetectors appear to be promising architectures with a simple design for mid-infrared sensing operations at room temperature. We fabricated resonant tunneling devices with GaInAsSb absorbers that allow operation in the 2-4 μm range with significant electrical responsivity of 0.97 A/W at 2004 nm to optical readout. This paper characterizes the photosensor response contrasting different operational regimes and offering a comprehensive theoretical analysis of the main physical ingredients that rule the sensor functionalities and affect its performance. We demonstrate how the drift, accumulation, and escape efficiencies of photogenerated carriers influence the electrostatic modulation of the sensor's electrical response and how they allow controlling the device's sensing abilities.},
  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}
}