@article{3888,
  abstract     = {{We successfully developed a process to fabricate freestanding cubic aluminium nitride (c-AlN) membranes containing cubic gallium nitride (c-GaN) quantum dots (QDs). The samples were grown by plasma assisted molecular beam epitaxy (MBE). To realize the photonic crystal (PhC) membrane we have chosen a triangular array of holes. The array was fabricated by electron beam lithography and several steps of reactive ion etching (RIE) with the help of a hard mask and an undercut of the active layer. The r/a- ratio of 0.35 was deter- mined by numerical simulations to obtain a preferably wide photonic band gap. Micro-photoluminescence (μ-PL) measurements of the photonic crystals, in particular of a H1 and a L3 cavity, and the emission of the QD ensemble were performed to characterize the samples. The PhCs show high quality factors of 4400 for the H1 cavity and about 5000/3000 for two different modes of the L3 cavity, respectively. The energy of the fundamental modes is in good agreement to the numerical simulations. }},
  author       = {{Blumenthal, Sarah and Bürger, Matthias and Hildebrandt, Andre and Förstner, Jens and Weber, Nils and Meier, Cedrik and Reuter, Dirk and As, Donat J.}},
  issn         = {{1862-6351}},
  journal      = {{physica status solidi (c)}},
  keywords     = {{tet_topic_phc, tet_topic_qd}},
  number       = {{5-6}},
  pages        = {{292--296}},
  publisher    = {{Wiley}},
  title        = {{{Fabrication and characterization of two-dimensional cubic AlN photonic crystal membranes containing zincblende GaN quantum dots}}},
  doi          = {{10.1002/pssc.201600010}},
  volume       = {{13}},
  year         = {{2016}},
}

@article{3963,
  abstract     = {{Whispering gallery modes (WGMs) were observed in 60 nm thin cubic AlN microdisk resonators containing a single layer of non-polar cubic GaN quantum dots. Freestanding microdisks were patterned by means of electron beam lithography and a two step reactive ion etching process. Micro-photoluminescence spectroscopy investigations were performed for optical characterization. We analyzed the mode spacing for disk diameters ranging from 2-4 lm. Numerical investigations using three dimensional finite difference time domain calculations were in good agreement
with the experimental data. Whispering gallery modes of the radial orders 1 and 2 were identified by means of simulated mode field distributions.}},
  author       = {{Bürger, M. and Ruth, M. and Declair, S. and Förstner, Jens and Meier, Cedrik and As, Donat Josef}},
  issn         = {{0003-6951}},
  journal      = {{Applied Physics Letters}},
  keywords     = {{tet_topic_qd, tet_topic_microdisk}},
  number       = {{8}},
  pages        = {{081105}},
  publisher    = {{AIP Publishing}},
  title        = {{{Whispering gallery modes in zinc-blende AlN microdisks containing non-polar GaN quantum dots}}},
  doi          = {{10.1063/1.4793653}},
  volume       = {{102}},
  year         = {{2013}},
}

@article{13568,
  author       = {{Mietze, C. and Landmann, M. and Rauls, E. and Machhadani, H. and Sakr, S. and Tchernycheva, M. and Julien, F. H. and Schmidt, Wolf Gero and Lischka, K. and As, Donat Josef}},
  issn         = {{1098-0121}},
  journal      = {{Physical Review B}},
  number       = {{19}},
  title        = {{{Band offsets in cubic GaN/AlN superlattices}}},
  doi          = {{10.1103/physrevb.83.195301}},
  volume       = {{83}},
  year         = {{2011}},
}

@article{13835,
  author       = {{Scholle, A. and Greulich-Weber, S. and As, Donat Josef and Mietze, Ch. and Son, N. T. and Hemmingsson, C. and Monemar, B. and Janzén, E. and Gerstmann, Uwe and Sanna, S. and Rauls, E. and Schmidt, Wolf Gero}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  number       = {{7}},
  pages        = {{1728--1731}},
  title        = {{{Magnetic characterization of conductance electrons in GaN}}},
  doi          = {{10.1002/pssb.200983582}},
  volume       = {{247}},
  year         = {{2010}},
}

@inproceedings{4218,
  abstract     = {{In this work we focus on the fabrication of ohmic contacts and of Schottky barrier devices (SBD) on non-polar cubic GaN epilayers grown by molecular beam epitaxy (MBE). A Ti/Al/Ni/Au metallization was used for ohmic contacts and the contact resistance was measured by transmission line measurements (TLM). Ni, Pd, Ag and NiSi Schottky barrier devices 300 µm in diameter were fabricated by thermal evaporation using contact lithography on cubic GaN epilayers. The current-voltage (I-V) and the capacity-voltage (C-V) characteristics were studied at room temperature in detail. A clear rectifying behavior was measured in all SBDs. In the Ni and Ag SBDs an abnormal large leakage current under reverse bias was observed. Isochronal thermal annealing of these Ni and Ag based SBDs at 200°C in air improved the reverse characteristics by up to three orders of magnitude. This is in contrast to the Pd contacts, where the as grown contact showed already good performance and thermal annealing had nearly no influence on the I-V characteristics. For all SBDs the magnitude of the reverse current is generally larger than that expected due to thermionic emission and an exponential increase of the reverse current is observed with increasing reverse voltage. In-depth analysis of the I-V characteristic showed that a thin surface barrier is formed at the metal semiconductor interface and that crystal defects like dislocations may be the reasons for the discrepancy between experimental data and thermionic emission theory. }},
  author       = {{As, Donat J. and Tschumak, Elena and Laubenstein, Irina and Kemper, Ricarda M. and Lischka, Klaus}},
  booktitle    = {{Materials Research Society Symposium Proceedings}},
  pages        = {{3--8}},
  publisher    = {{Materials Research Society}},
  title        = {{{Schottky and Ohmic Contacts on Non-Polar Cubic GaN Epilayers}}},
  doi          = {{10.1557/proc-1108-a01-02}},
  volume       = {{1108}},
  year         = {{2009}},
}