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@PHDTHESIS{vondenDriesch:717204,
      author       = {von den Driesch, Nils},
      othercontributors = {Mantl, Siegfried and Stampfer, Christoph},
      title        = {{E}pitaxy of group {IV} {S}i-{G}e-{S}n alloys for advanced
                      heterostructure light emitters},
      volume       = {163},
      school       = {RWTH Aachen University},
      type         = {Dissertation},
      address      = {Jülich},
      publisher    = {Forschungszentrum Jülich GmbH, Zentralbibliothek},
      reportid     = {RWTH-2018-221225},
      series       = {Schriften des Forschungszentrums Jülich. Reihe
                      Schlüsseltechnologien/key technologies},
      pages        = {1 Online-Ressource (viii, 149 Seiten) : Illustrationen,
                      Diagramme},
      year         = {2018},
      note         = {Druckausgabe: 2018. - Onlineausgabe: 2018. - Auch
                      veröffentlicht auf dem Publikationsserver der RWTH Aachen
                      University; Dissertation, RWTH Aachen University, 2018},
      abstract     = {Over the last decades, silicon-based integrated circuits
                      underpinned information technology. To keep up with the
                      demand for faster and, becoming increasingly more relevant
                      nowadays, energy-efficient electronics, smart solutions
                      targeting power consumption are required. Integration of
                      photonic components, e.g. for replacing part of copper
                      interconnects, could strongly reduce on-chip dissipation.
                      Prerequisite for efficient active optoelectronic devices,
                      however not available in group IV elements, is a direct
                      bandgap. Only recently though, a truly silicon-compatible
                      solution was demonstrated by tin-based group IV GeSn alloys,
                      which offer a direct bandgap for a cubic lattice and Sn
                      concentrations above 9 $at.\%.$ Nevertheless, when moving
                      from an experimental direct bandgap demonstration towards
                      readily integrated light emitters, plenty of challenges have
                      to be overcome. In this work, some of the remaining key
                      aspects are investigated. Reduced-pressure chemical vapor
                      deposition on 200 mm (Ge-buffered) Si wafers was used to
                      form the investigated Si-Ge-Sn alloys. GeSn layers with
                      subtitutionally incorporated Sn concentrations up to 14
                      $at.\%,$ considerably exceeding the solid solubility limit
                      of 1 $at.\%$ Sn in Ge, were epitaxially grown to study
                      growth kinetics. The necessary strain relieve in GeSn
                      binaries was studied growing layers with thicknesses up to 1
                      µm, well above the critical thickness for strain
                      relaxation. Influence of both, Sn incorporation and residual
                      strain, on the optical properties was probed using
                      temperature-dependent photoluminescence and reflection
                      spectroscopy. Mid infrared light emission was found at
                      wavelengths as long as 3.4 µm (0.37 eV) at room
                      temperature. Overall, the investigated GeSn material system
                      allows to cover a range up to about 2 µm (0.60 eV), making
                      these binaries also interesting for a multitude of chemical
                      and biological sensing applications. Efficient light sources
                      further require the confinement of carriers in
                      heterostructures. Therefore, also epitaxy of SiGeSn
                      ternaries, which previously have been identified as optimal
                      larger bandgap claddings, was scrutinized. The additional
                      degree of compositional freedom was demonstrated by bandgap
                      engineering, individually using strain relaxation, Si and Sn
                      composition. Combining GeSn binaries and SiGeSn ternaries
                      allowed formation of different diode structures. Light
                      emitting diodes, both from GeSn homojunctions and multi
                      quantum well heterojunctions, were epitaxially grown and
                      studied for their emission characteristics. One drawback in
                      these structures, however, is that they do not just yet
                      feature a direct bandgap. Finally, several (so far undoped)
                      direct bandgap GeSn/SiGeSn double heterostructures and multi
                      quantum wells were investigated. The importance of defect
                      engineering, that is separation of unavoidable misfit
                      defects and active device regions, is stressed and fathomed
                      for both designs. Excellent structural properties of the
                      grown layers were proven by advanced characterization
                      techniques, such as atom probe tomography or dark-field
                      electron holography. Photoluminescence measurements were
                      carried out to probe the optical quality of those
                      structures, revealing strongly enhanced light emission from
                      MQW structures, compared to bulk GeSn layers.},
      cin          = {080009 / 130000 / 139320},
      ddc          = {530},
      cid          = {$I:(DE-82)080009_20140620$ / $I:(DE-82)130000_20140620$ /
                      $I:(DE-82)139320_20140620$},
      typ          = {PUB:(DE-HGF)11 / PUB:(DE-HGF)3},
      doi          = {10.18154/RWTH-2018-221225},
      url          = {https://publications.rwth-aachen.de/record/717204},
}