113 citations · 588 across the 30 of their papers we have counts for
30 papers
Atomic-scale composition of the ternary III-V semiconductor (Al,Ga)Sb visualized by cross-sectional scanning tunneling microscopy
Hitesh Kumar, Vladimir Kaganer, Zijin Lei +3
Cross-sectional scanning tunneling microscopy at 5 K is used to investigate cation mixing in (Al,Ga)Sb layers grown by molecular beam epitaxy, via direct atom counting at the (1-10…
Dislocation correlations in GaN epitaxial films revealed by EBSD and XRD
Vladimir M. Kaganer, Domenik Spallek, Philipp John +2
Correlations between dislocations in crystals reduce the elastic energy via screening of the strain by the surrounding dislocations. We study the correlations of threading dislocat…
ScN/GaN(): a new platform for the epitaxy of twin-free metal-semiconductor heterostructures
Philipp John, Achim Trampert, Duc Van Dinh +6
We study the molecular beam epitaxy of rock-salt ScN on the wurtzite GaN() surface. To this end, ScN is grown on free-standing GaN() substrates and self-ass…
Self-regulated radius of spontaneously formed GaN nanowires in molecular beam epitaxy
Sergio Fernández-Garrido, Vladimir M. Kaganer, Karl K. Sabelfeld +5
We investigate the axial and radial growth of GaN nanowires upon a variation of the Ga flux during molecular beam epitaxial growth. An increase in the Ga flux promotes radial growt…
X-ray diffraction from dislocation half-loops in epitaxial films
Vladimir M. Kaganer
X-ray diffraction from dislocation half-loops consisting of a misfit segment and two threading arms extending from it to the surface is calculated by the Monte Carlo method. The di…
A route for the top-down fabrication of ordered ultrathin GaN nanowires
Miriam Oliva, Vladimir Kaganer, Maximilian Pudelski +5
Ultrathin GaN nanowires (NWs) are attractive to maximize surface effects and as building block in high-frequency transistors. Here, we introduce a facile route for the top-down fab…
X-ray scattering study of GaN nanowires grown on Ti/AlO by molecular beam epitaxy
Vladimir M. Kaganer, Oleg V. Konovalov, Gabriele Calabrese +5
GaN nanowires (NWs) grown by molecular beam epitaxy on Ti films sputtered on AlO are studied by X-ray diffraction (XRD) and grazing incidence small-angle X-ray scatteri…
Nanoscale mapping of the full strain tensor, rotation and composition in partially relaxed InGaN layers by scanning X-ray diffraction microscopy
Carsten Richter, Vladimir M. Kaganer, Armelle Even +5
Strain and composition play a fundamental role in semiconductor physics, since they are means to tune the electronic and optical properties of a material and hence develop new devi…
Carrier diffusion in GaN -- a cathodoluminescence study. III: Nature of nonradiative recombination at threading dislocations
Jonas Lähnemann, Vladimir M. Kaganer, Karl K. Sabelfeld +5
We investigate the impact of threading dislocations with an edge component (a or a+c-type) on carrier recombination and diffusion in GaN(0001) layers close to the surface as well a…
Carrier diffusion in GaN -- a cathodoluminescence study. II: Ambipolar vs. exciton diffusion
Oliver Brandt, Vladimir M. Kaganer, Jonas Lähnemann +8
We determine the diffusion length of excess carriers in GaN by spatially resolved cathodoluminescence spectroscopy utilizing a single quantum well as carrier collector or carrier s…
Resolution of a bent-crystal spectrometer for X-ray free electron laser pulses: diamond vs. silicon
Vladimir Kaganer, Ilia Petrov, Liubov Samoylova
The resolution function of a spectrometer based on a strongly bent single crystal (bending radius of 10 cm or less) is evaluated. It is shown that the resolution is controlled by t…
Small-angle X-ray scattering from GaN nanowires on Si(111): facet truncation rods, facet roughness, and Porod's law
Vladimir M. Kaganer, Oleg V. Konovalov, Sergio Fernández-Garrido
Small-angle X-ray scattering from GaN nanowires grown on Si(111) is studied experimentally and modeled by means of Monte Carlo simulations. It is shown that the scattering intensit…
Radius-Dependent Homogeneous Strain in Uncoalesced GaN Nanowires
G. Calabrese, D. van Treeck, V. M. Kaganer +6
We investigate the strain state of ensembles of thin and nearly coalescence-free self-assembled GaN nanowires prepared by plasma-assisted molecular beam epitaxy on Ti/AlO$_{3…
Carrier diffusion in GaN -- a cathodoluminescence study. I: Temperature-dependent generation volume
Uwe Jahn, Vladimir M. Kaganer, Karl K. Sabelfeld +8
The determination of the carrier diffusion length of semiconductors such as GaN and GaAs by cathodoluminescence imaging requires accurate knowledge about the spatial distribution o…
Determination of the carrier diffusion length in GaN from cathodoluminescence maps around threading dislocations: fallacies and opportunities
Vladimir M. Kaganer, Jonas Lähnemann, Carsten Pfüller +3
We investigate, both theoretically and experimentally, the drift, diffusion, and recombination of excitons in the strain field of an edge threading dislocation intersecting the GaN…
X-ray diffraction from strongly bent crystals and spectroscopy of XFEL pulses
Vladimir Kaganer, Ilia Petrov, Liubov Samoylova
The use of strongly bent crystals in spectrometers for pulses of a hard x-ray free-electron laser is explored theoretically. Diffraction is calculated in both dynamical and kinemat…
Piezoelectric field, exciton lifetime, and cathodoluminescence intensity at threading dislocations in GaN{0001}
Vladimir M. Kaganer, Karl K. Sabelfeld, Oliver Brandt
The strain field of a dislocation emerging at a free surface is partially relaxed to ensure stress free boundary conditions. We show that this relaxation strain at the outcrop of e…
Self-Assembled formation of long, thin, and uncoalesced GaN nanowires on crystalline TiN films
David van Treeck, Gabriele Calabrese, Jelle J. W. Goertz +4
We investigate in detail the self-assembled nucleation and growth of GaN nanowires by molecular beam epitaxy on crystalline TiN films. We demonstrate that this type of substrate al…
Bunches of misfit dislocations on the onset of relaxation of SiGe/Si(001) epitaxial films revealed by high-resolution x-ray diffraction
Vladimir Kaganer, Tatjana Ulyanenkova, Andrei Benediktovitch +2
The experimental x-ray diffraction patterns of a SiGe/Si(001) epitaxial film with a low density of misfit dislocations are modeled by the Monte Carlo method. It is…
Ga-polar (In,Ga)N/GaN quantum wells vs. N-polar (In,Ga)N quantum disks in GaN nanowires: Comparative analysis of carrier recombination, diffusion, and radiative efficiency
F. Feix, T. Flissikowski, K. K. Sabelfeld +5
We investigate the radiative and nonradiative recombination processes in planar (In,Ga)N/GaN(0001) quantum wells and (In,Ga)N quantum disks embedded in GaN nanowires…
Dislocation contrast in cathodoluminescence and electron-beam induced current maps on GaN(0001)
K. K. Sabelfeld, V. M. Kaganer, C. Pfüller +1
We theoretically analyze the contrast observed at the outcrop of a threading dislocation at the GaN(0001) surface in cathodoluminescence and electron-beam induced current maps. We…
Elastic vs. plastic strain relaxation in coalesced GaN nanowires: an x-ray diffraction study
Vladimir M. Kaganer, Bernd Jenichen, Oliver Brandt
The coalescence in dense arrays of spontaneously formed GaN nanowires proceeds by bundling: adjacent nanowires bend and merge at their top, thus reducing their surface energy at th…
Influence of strain relaxation in axial (In,Ga)N/GaN nanowire heterostructures on their electronic properties
Oliver Marquardt, Thilo Krause, Vladimir Kaganer +3
We present a systematic study of the influence of elastic strain relaxation on the built-in electrostatic potentials and the electronic properties of axial (In,Ga)N/GaN nanowire he…
Correlation between the structural and optical properties of spontaneously formed GaN nanowires: a quantitative evaluation of the impact of nanowire coalescence
S. Fernández-Garrido, V. M. Kaganer, C. Hauswald +5
We investigate the structural and optical properties of spontaneously formed GaN nanowires with different degrees of coalescence. This quantity is determined by an analysis of the…