Philipp Drechsel
Osram Opto Semiconductors GmbH
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Featured researches published by Philipp Drechsel.
Applied Physics Letters | 2012
Bastian Galler; Philipp Drechsel; R. Monnard; P. Rode; P. Stauss; S. Froehlich; Werner Bergbauer; Michael Binder; Matthias Sabathil; Berthold Hahn; J. Wagner
High-efficiency InGaN-based light-emitting diodes have been grown on (111) silicon substrates and investigated with regard to efficiency and carrier lifetime as a function of current density. Using a single quantum well active layer ensures a well-defined active volume which enables the precise determination of the recombination coefficients in the ABC rate model for different emission wavelengths and junction temperatures. Good agreement of the resulting C values with calculated Auger coefficients is found both with respect to absolute value as well as their dependence on bandgap energy and temperature.
Journal of Applied Physics | 2012
S. Fritze; Philipp Drechsel; Peter Stauss; Patrick Rode; T. Markurt; Tobias Schulz; M. Albrecht; J. Bläsing; Armin Dadgar; A. Krost
Thin AlGaN interlayers have been grown into a thick GaN stack on Si substrates to compensate tensile thermal stress and significantly improve the structural perfection of the GaN. In particular, thicker interlayers reduce the density in a-type dislocations as concluded from x-ray diffraction (XRD) measurements. Beyond an interlayer thickness of 28 nm plastic substrate deformation occurs. For a thick GaN stack, the first two interlayers serve as strain engineering layers to obtain a crack-free GaN structure, while a third strongly reduces the XRD ω-(0002)-FWHM. The vertical strain and quality profile determined by several XRD methods demonstrates the individual impact of each interlayer.
Applied Physics Letters | 2014
Tobias Schulz; Anna Nirschl; Philipp Drechsel; Felix Nippert; T. Markurt; M. Albrecht; A. Hoffmann
The recombination dynamics of InxGa1−xN single quantum wells are investigated. By comparing the photoluminescence (PL) decay spectra with simulated emission spectra obtained by a Schrodinger-Poisson approach, we give evidence that recombination from higher subbands contributes the emission of the quantum well at high excitation densities. This recombination path appears as a shoulder on the high energy side of the spectrum at high charge carrier densities and exhibits decay in the range of ps. Due to the lower confinement of the excited subband states, a distinct proportion of the probability density function lies outside the quantum well, thus contributing to charge carrier loss. By estimating the current density in our time resolved PL experiments, we show that the onset of this loss mechanism occurs in the droop relevant regime above 20 A/cm2.
Journal of Applied Physics | 2018
T. Markurt; Tobias Schulz; Philipp Drechsel; Peter Stauss; M. Albrecht
In this work, we present an experimental and theoretical study of the process of plastic strain relaxation of (0001)-oriented wurtzite heterostructures. By means of transmission electron microscopy and atomic force microscopy, we show that plastic relaxation of tensile strained AlxGa1-xN/GaN heterostructures proceeds predominantly by nucleation of a-type misfit dislocations in the 1 3 ⟨ 11 2 ¯ 0 ⟩ | 0001 slip-system driven by a three-dimensional surface morphology, either due to island growth or due to cracking of the layer. Based on our experimental results, we derive a quantitative model for the dislocation nucleation process. With the shear stress gradients at the nucleation sites of a-type misfit dislocations obtained by the finite element method, we calculate the critical thickness for plastic relaxation of strained wurtzite films and heterostructures as dependent on the surface morphology. The crucial role of the growth mode of the film on the strain relaxation process and the resulting consequences is discussed in the paper.In this work, we present an experimental and theoretical study of the process of plastic strain relaxation of (0001)-oriented wurtzite heterostructures. By means of transmission electron microscopy and atomic force microscopy, we show that plastic relaxation of tensile strained AlxGa1-xN/GaN heterostructures proceeds predominantly by nucleation of a-type misfit dislocations in the 1 3 ⟨ 11 2 ¯ 0 ⟩ | 0001 slip-system driven by a three-dimensional surface morphology, either due to island growth or due to cracking of the layer. Based on our experimental results, we derive a quantitative model for the dislocation nucleation process. With the shear stress gradients at the nucleation sites of a-type misfit dislocations obtained by the finite element method, we calculate the critical thickness for plastic relaxation of strained wurtzite films and heterostructures as dependent on the surface morphology. The crucial role of the growth mode of the film on the strain relaxation process and the resulting ...
Physica Status Solidi B-basic Solid State Physics | 2013
Dario Schiavon; Michael Binder; Matthias Peter; Bastian Galler; Philipp Drechsel; F. Scholz
Physical Review Letters | 2013
T. Markurt; Liverios Lymperakis; Jörg Neugebauer; Philipp Drechsel; Peter Stauß; Tobias Schulz; T. Remmele; Vincenzo Grillo; Enzo Rotunno; M. Albrecht
Physica Status Solidi (a) | 2012
Philipp Drechsel; Peter Stauss; Werner Bergbauer; Patrick Rode; S. Fritze; A. Krost; T. Markurt; Tobias Schulz; M. Albrecht; H. Riechert; Ulrich Steegmüller
Archive | 2010
Peter Stauss; Philipp Drechsel
Physica Status Solidi (c) | 2011
Christopher Kölper; Werner Bergbauer; Philipp Drechsel; Matthias Sabathil; Martin Straßburg; Hans-Jürgen Lugauer; Bernd Witzigmann; Sönke Fündling; Shunfeng Li; H.-H. Wehmann; A. Waag
Archive | 2011
Peter Stauß; Philipp Drechsel