@article{46573,
  abstract     = {{<jats:p>An ultra-fast change of the absorption onset for zincblende gallium-nitride (zb-GaN) (fundamental bandgap: 3.23 eV) is observed by investigating the imaginary part of the dielectric function using time-dependent femtosecond pump–probe spectroscopic ellipsometry between 2.9 and 3.7 eV. The 266 nm (4.66 eV) pump pulses induce a large electron–hole pair concentration up to 4×1020cm−3, which shift the transition energy between conduction and valence bands due to many-body effects up to ≈500 meV. Here, the absorption onset increases due to band filling while the bandgap renormalization at the same time decreases the bandgap. Additionally, the absorption of the pump-beam creates a free-carrier profile within the 605 nm zb-GaN layer with high free-carrier concentrations at the surface, and low concentrations at the interface to the substrate. This leads to varying optical properties from the sample surface (high transition energy) to substrate (low transition energy), which are taken into account by grading analysis for an accurate description of the experimental data. For this, a model describing the time- and position-dependent free-carrier concentration is formulated by considering the relaxation, recombination, and diffusion of those carriers. We provide a quantitative analysis of optical experimental data (ellipsometric angles Ψ and Δ) as well as a plot for the time-dependent change of the imaginary part of the dielectric function.</jats:p>}},
  author       = {{Baron, Elias and Goldhahn, Rüdiger and Espinoza, Shirly and Zahradník, Martin and Rebarz, Mateusz and Andreasson, Jakob and Deppe, Michael and As, Donat Josef and Feneberg, Martin}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  keywords     = {{General Physics and Astronomy}},
  number       = {{7}},
  publisher    = {{AIP Publishing}},
  title        = {{{Time-resolved pump–probe spectroscopic ellipsometry of cubic GaN. I. Determination of the dielectric function}}},
  doi          = {{10.1063/5.0153091}},
  volume       = {{134}},
  year         = {{2023}},
}

@article{46132,
  author       = {{Littmann, Mario and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}},
  number       = {{7}},
  publisher    = {{Wiley}},
  title        = {{{Remote Epitaxy of Cubic Gallium Nitride on Graphene‐Covered 3C‐SiC Substrates by Plasma‐Assisted Molecular Beam Epitaxy}}},
  doi          = {{10.1002/pssb.202300034}},
  volume       = {{260}},
  year         = {{2023}},
}

@article{46741,
  author       = {{Zscherp, Mario Fabian and Jentsch, Silas Aurel and Müller, Marius Johannes and Lider, Vitalii and Becker, Celina and Chen, Limei and Littmann, Mario and Meier, Falco and Beyer, Andreas and Hofmann, Detlev Michael and As, Donat Josef and Klar, Peter Jens and Volz, Kerstin and Chatterjee, Sangam and Schörmann, Jörg}},
  issn         = {{1944-8244}},
  journal      = {{ACS Applied Materials &amp; Interfaces}},
  keywords     = {{General Materials Science}},
  number       = {{33}},
  pages        = {{39513--39522}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Overcoming the Miscibility Gap of GaN/InN in MBE Growth of Cubic In<sub><i>x</i></sub>Ga<sub>1–<i>x</i></sub>N}}},
  doi          = {{10.1021/acsami.3c06319}},
  volume       = {{15}},
  year         = {{2023}},
}

@article{35232,
  author       = {{Meier, Falco and Littmann, Mario and Bürger, Julius and Riedl, Thomas and Kool, Daniel and Lindner, Jörg and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}},
  publisher    = {{Wiley}},
  title        = {{{Selective Area Growth of Cubic Gallium Nitride in Nanoscopic Silicon Dioxide Masks}}},
  doi          = {{10.1002/pssb.202200508}},
  year         = {{2022}},
}

@article{23842,
  author       = {{Baron, Elias and Feneberg, Martin and Goldhahn, Rüdiger and Deppe, Michael and Tacken, Fabian and As, Donat Josef}},
  issn         = {{0022-3727}},
  journal      = {{Journal of Physics D: Applied Physics}},
  title        = {{{Optical evidence of many-body effects in the zincblende Al$_\mathrm{x}$Ga$_\mathrm{1-x}$N alloy system}}},
  doi          = {{10.1088/1361-6463/abb97a}},
  year         = {{2021}},
}

@article{25227,
  abstract     = {{<jats:title>Abstract</jats:title><jats:p>Quantum well (QW) heterostructures have been extensively used for the realization of a wide range of optical and electronic devices. Exploiting their potential for further improvement and development requires a fundamental understanding of their electronic structure. So far, the most commonly used experimental techniques for this purpose have been all-optical spectroscopy methods that, however, are generally averaging in momentum space. Additional information can be gained by angle-resolved photoelectron spectroscopy (ARPES), which measures the electronic structure with momentum resolution. Here we report on the use of extremely low-energy ARPES (photon energy ~ 7 eV) to increase depth sensitivity and access buried QW states, located at 3 nm and 6 nm below the surface of cubic-GaN/AlN and GaAs/AlGaAs heterostructures, respectively. We find that the QW states in cubic-GaN/AlN can indeed be observed, but not their energy dispersion, because of the high surface roughness. The GaAs/AlGaAs QW states, on the other hand, are buried too deep to be detected by extremely low-energy ARPES. Since the sample surface is much flatter, the ARPES spectra of the GaAs/AlGaAs show distinct features in momentum space, which can be reconducted to the band structure of the topmost surface layer of the QW structure. Our results provide important information about the samples’ properties required to perform extremely low-energy ARPES experiments on electronic states buried in semiconductor heterostructures.</jats:p>}},
  author       = {{Hajlaoui, Mahdi and Ponzoni, Stefano and Deppe, Michael and Henksmeier, Tobias and As, Donat Josef and Reuter, Dirk and Zentgraf, Thomas and Springholz, Gunther and Schneider, Claus Michael and Cramm, Stefan and Cinchetti, Mirko}},
  issn         = {{2045-2322}},
  journal      = {{Scientific Reports}},
  title        = {{{Extremely low-energy ARPES of quantum well states in cubic-GaN/AlN and GaAs/AlGaAs heterostructures}}},
  doi          = {{10.1038/s41598-021-98569-6}},
  volume       = {{11}},
  year         = {{2021}},
}

@article{23843,
  author       = {{Meier, F. and Protte, M. and Baron, E. and Feneberg, M. and Goldhahn, R. and Reuter, Dirk and As, Donat Josef}},
  issn         = {{2158-3226}},
  journal      = {{AIP Advances}},
  title        = {{{Selective area growth of cubic gallium nitride on silicon (001) and 3C-silicon carbide (001)}}},
  doi          = {{10.1063/5.0053865}},
  year         = {{2021}},
}

@article{23838,
  author       = {{Beloufa, Abbes and Bouguenna, Driss and Kermas, Nawel and As, Donat Josef}},
  issn         = {{0361-5235}},
  journal      = {{Journal of Electronic Materials}},
  pages        = {{2008--2017}},
  title        = {{{A Physics-Based Compact Static and Dynamic Characteristics Model for Al2O3/InxAl1−xN/AlN/GaN MOS-HEMTs}}},
  doi          = {{10.1007/s11664-019-07927-8}},
  year         = {{2020}},
}

@article{23840,
  author       = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  title        = {{{Photoluminescence Line‐Shape Analysis of Highly n‐Type Doped Zincblende GaN}}},
  doi          = {{10.1002/pssb.201900522}},
  year         = {{2020}},
}

@article{23841,
  author       = {{Deppe, Michael and Henksmeier, Tobias and Gerlach, Jürgen W. and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  title        = {{{Molecular Beam Epitaxy Growth and Characterization of Germanium‐Doped Cubic Al                          x                        Ga            1−                          x                        N}}},
  doi          = {{10.1002/pssb.201900532}},
  year         = {{2020}},
}

@article{23831,
  author       = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  title        = {{{Influence of the free-electron concentration on the optical properties of zincblende GaN up to 1×1020cm−3}}},
  doi          = {{10.1103/physrevmaterials.3.104603}},
  year         = {{2019}},
}

@article{8646,
  author       = {{Deppe, M. and Gerlach, J. W. and Shvarkov, S. and Rogalla, D. and Becker, H.-W. and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  title        = {{{Germanium doping of cubic GaN grown by molecular beam epitaxy}}},
  doi          = {{10.1063/1.5066095}},
  year         = {{2019}},
}

@article{13965,
  author       = {{Buß, J. H. and Schupp, T. and As, Donat Josef and Hägele, D. and Rudolph, J.}},
  issn         = {{0021-8979}},
  journal      = {{Journal of Applied Physics}},
  title        = {{{Optical excitation density dependence of spin dynamics in bulk cubic GaN}}},
  doi          = {{10.1063/1.5123914}},
  year         = {{2019}},
}

@article{13966,
  author       = {{Baron, Elias and Goldhahn, Rüdiger and Deppe, Michael and As, Donat Josef and Feneberg, Martin}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  title        = {{{Influence of the free-electron concentration on the optical properties of zincblende GaN up to 1×1020cm−3}}},
  doi          = {{10.1103/physrevmaterials.3.104603}},
  year         = {{2019}},
}

@article{15444,
  author       = {{Deppe, Michael and Henksmeier, Tobias and Gerlach, Jürgen W. and Reuter, Dirk and As, Donat J.}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  title        = {{{Molecular Beam Epitaxy Growth and Characterization of Germanium‐Doped Cubic Al                          x                        Ga            1−                          x                        N}}},
  doi          = {{10.1002/pssb.201900532}},
  year         = {{2019}},
}

@article{4809,
  author       = {{Herval, Leonilson K.S. and de Godoy, Marcio P.F. and Wecker, Tobias and As, Donat Josef}},
  issn         = {{0022-2313}},
  journal      = {{Journal of Luminescence}},
  pages        = {{309--313}},
  publisher    = {{Elsevier BV}},
  title        = {{{Investigation on interface-related defects by photoluminescence of cubic (Al)GaN/AlN multi-quantum wells structures}}},
  doi          = {{10.1016/j.jlumin.2018.02.051}},
  volume       = {{198}},
  year         = {{2018}},
}

@article{7022,
  author       = {{Blumenthal, Sarah and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  number       = {{5}},
  publisher    = {{Wiley}},
  title        = {{{Optical Properties of Cubic GaN Quantum Dots Grown by Molecular Beam Epitaxy}}},
  doi          = {{10.1002/pssb.201700457}},
  volume       = {{255}},
  year         = {{2018}},
}

@inbook{4350,
  author       = {{As, Donat Josef and Lischka, Klaus}},
  booktitle    = {{Molecular Beam Epitaxy}},
  isbn         = {{9780128121368}},
  pages        = {{95--114}},
  publisher    = {{Elsevier}},
  title        = {{{Nonpolar Cubic III-nitrides: From the Basics of Growth to Device Applications}}},
  doi          = {{10.1016/b978-0-12-812136-8.00006-2}},
  year         = {{2018}},
}

@article{20588,
  abstract     = {{We have investigated the stacking of self-assembled cubic GaN quantum dots (QDs) grown in Stranski–Krastanov (SK) growth mode. The number of stacked layers is varied to compare their optical properties. The growth is in situ controlled by reflection high energy electron diffraction to prove the SK QD growth. Atomic force and transmission electron microscopy show the existence of wetting layer and QDs with a diameter of about 10 nm and a height of about 2 nm. The QDs have a truncated pyramidal form and are vertically aligned in growth direction. Photoluminescence measurements show an increase of the intensity with increasing number of stacked QD layers. Furthermore, a systematic blue-shift of 120 meV is observed with increasing number of stacked QD layers. This blueshift derives from a decrease in the QD height, because the QD height has also been the main confining dimension in our QDs.}},
  author       = {{Blumenthal, Sarah and Rieger, Torsten and Meertens, Doris and Pawlis, Alexander and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{cubic crystals, GaN, molecular beam epitaxy, quantum dots}},
  number       = {{3}},
  pages        = {{1600729}},
  title        = {{{Stacked Self-Assembled Cubic GaN Quantum Dots Grown by Molecular Beam Epitaxy}}},
  doi          = {{https://doi.org/10.1002/pssb.201600729}},
  volume       = {{255}},
  year         = {{2018}},
}

@article{4808,
  author       = {{Wecker, Tobias and Callsen, Gordon and Hoffmann, Axel and Reuter, Dirk and As, Donat Josef}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  number       = {{5}},
  publisher    = {{Wiley}},
  title        = {{{Correlation of the Carrier Decay Time and Barrier Thickness for Asymmetric Cubic GaN/Al0.64Ga0.36N Double Quantum Wells}}},
  doi          = {{10.1002/pssb.201700373}},
  volume       = {{255}},
  year         = {{2017}},
}