A5045887239- GaN-based semiconductor devices and materials
- ZnO doping and properties
- Molecular Junctions and Nanostructures
- Surface and Thin Film Phenomena
- Ga2O3 and related materials
- Electronic and Structural Properties of Oxides
- Crystal Structures and Properties
- Semiconductor materials and devices
- X-ray Diffraction in Crystallography
- Machine Learning in Materials Science
- Optical Coatings and Gratings
- Microwave Dielectric Ceramics Synthesis
- Semiconductor materials and interfaces
- Catalytic Processes in Materials Science
- Phase-change materials and chalcogenides
- Surface Chemistry and Catalysis
- Chalcogenide Semiconductor Thin Films
- Organic Electronics and Photovoltaics
- Electron and X-Ray Spectroscopy Techniques
- Multiferroics and related materials
- Advanced Chemical Physics Studies
- Advanced Materials Characterization Techniques
- Ammonia Synthesis and Nitrogen Reduction
- Glass properties and applications
- Chemical and Physical Properties of Materials
Paderborn University
2009-2018
Technische Universität Dresden
2013
University of Freiburg
2013
Institute of High Performance Computing
2013
University of Stuttgart
2013
Computing Center
2013
In this study, we present a combined density functional theory and many-body perturbation study on the electronic optical properties of TiO2 brookite as well tetragonal phases rutile anatase. The structure linear response have been calculated from Kohn–Sham band applying (semi)local nonlocal screened hybrid exchange–correlation functionals. Single-particle excitations are treated within GW approximation for independent quasiparticles. For calculations, two-particle included by solving...
We have investigated the structural and electronic properties as well linear optical response of amorphous TiO${}_{2}$ within density functional theory a numerically efficient based tight-binding approach many-body perturbation theory. The disordered phase is modeled by molecular dynamics. equivalence to experimentally characterized phases demonstrated atomic structure factors radial pair-distribution functions. By calculations, using both semilocal Perdew-Burke-Ernzerhof nonlocal...
Density-functional-theory calculations are combined with many-body perturbation theory in order to elucidate the geometry, electronic, and optical properties of $wz\ensuremath{-}\mathrm{GaN}(1\overline{1}00$) surface, i.e., so-called $m$-plane. The absorption reflection anisotropy related electronic transitions between surface states identified by comparison measured data covering transition energies from 2.4 up 5.4 eV. Our results show a relaxation mechanism consistent electron counting...
The presently unknown band offset in nonpolar cubic GaN/AlN superlattices is investigated by inter-sub-band and interband spectroscopies as well ab initio calculations. On one hand, the conduction-band (CBO) has been determined from comparison of measured transition energies with model calculations within effective mass approximation. other valence-band (VBO) CBO are accurately simulated calculating many-body corrections $\mathit{GW}$ approximation on top hybrid-functional density functional...
The electronic and optical properties of zinc-blende (zb) Al${}_{x}$Ga${}_{1\ensuremath{-}x}$N over the whole alloy composition range are presented in a joint theoretical experimental study. Because zb-GaN is direct (${\ensuremath{\Gamma}}_{v}\ensuremath{\rightarrow}{\ensuremath{\Gamma}}_{c}$) semiconductor zb-AlN shows an indirect (${\ensuremath{\Gamma}}_{v}\ensuremath{\rightarrow}{X}_{c}$) fundamental band gap, ternary exhibits concentration-dependent direct-indirect gap crossing point...
Combining electron paramagnetic resonance, density functional theory, and positron annihilation spectroscopy (PAS), we identify the nitrogen interstitial defect in GaN. The isolated is unstable transforms into a split configuration $(\mathrm{N}\mathrm{\text{\ensuremath{-}}}\mathrm{N}{)}_{\mathrm{N}}$. It generated by particle irradiation with an introduction rate of primary defect, pins Fermi level at ${E}_{C}\ensuremath{-}1.0\text{ }\text{ }\mathrm{eV}$ for high fluences, anneals out...
We have investigated the structural and electronic properties of amorphous TiO2 using molecular dynamics (MD) simulations based on ab initio density functional theory, a numerically efficient density-functional-based tight-binding approach classical many-body potentials. The lower level approximations are successively validated by higher ones through comparison calculated properties. results reproduce all relevant features a-TiO2 as obtained quantum-mechanical simulation experimentally...
We present detailed density-functional theory studies of the structures clean Au(110) surfaces and energetics various atomic oxygen coverages. Various $(1\ifmmode\times\else\texttimes\fi{}r)$ ``missing row'' reconstructions surface have been investigated. The energies reconstructed are found to be very close with an energy minimum for $\text{Au}(110)\text{\ensuremath{-}}(1\ifmmode\times\else\texttimes\fi{}3)$. (111) microfacets formed at...
We perform a comprehensive theoretical study of the structural and electronic properties potassium niobate (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">K</mml:mi><mml:mi mathvariant="normal">N</mml:mi><mml:mi mathvariant="normal">b</mml:mi><mml:mi mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn mathvariant="normal">3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>) in cubic, tetragonal,...
The composition dependence of the natural band alignment at nonpolar ${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{N}/{\mathrm{Al}}_{y}{\mathrm{Ga}}_{1\ensuremath{-}y}\mathrm{N}$ heterojunctions is investigated via hybrid functional based density theory. Accurate band-gap data are provided using Heyd-Scuseria-Ernzerhof (HSE) type functionals with a dependent exact-exchange contribution. unstrained between zincblende (zb)...
Atomic length-scale order characteristics of binary and ternary amorphous oxides are presented within the framework ab initio theory. A combined numerically efficient density functional based tight-binding molecular dynamics theory approach is applied to model (a) phases SiO2 TiO2 as well phase atomically mixed TixSi1-xO2 hybrid-oxide alloys over entire composition range. Short mid-range in disordered material characterized by bond length bond-angle statistics, pair distribution function...
We present density functional theory calculations of the adsorption atomic oxygen on Au(110) surface. The stability adstructures various (1 × r) reconstructed surfaces has been investigated, considering experimentally typical ultrahigh vacuum (UHV) conditions. Three Au−O chainlike structures have identified to be especially stable under specific temperature and pressure These chain are clearly favored over conglomerates represent most form chemisorbed surfaces.