Prof. Holger T. Grahn Profile

Prof. Holger T. Grahn

Research Associate at Paul-Drude-Institut für Festkörperelektronik

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Publications (15)

Proceedings Article | 20 April 2017 Presentation

The 4.7-THz quantum-cascade laser local oscillator on SOFIA (Conference Presentation)

Heinz-Wilhelm Hübers, Heiko Richter, Martin Wienold, Lutz Schrottke, Klaus Biermann, Holger Grahn

Proceedings Volume 10123, 1012314 (2017) https://doi.org/10.1117/12.2253577

KEYWORDS: Observatories, Spectroscopy, Terahertz radiation, Oscillators, Astronomy, Heterodyning, Terahertz spectroscopy, Oxygen, Receivers, Infrared spectroscopy

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Proceedings Article | 10 March 2016 Paper

Frequency comb operation of long-cavity terahertz quantum-cascade lasers

M. Wienold, B. Röben, L. Schrottke, H. Grahn

Proceedings Volume 9767, 97671A (2016) https://doi.org/10.1117/12.2208128

KEYWORDS: Continuous wave operation, Semiconductor lasers, Quantum cascade lasers, Frequency combs, Spectroscopy, Laser applications, Terahertz radiation, Fourier transforms, Absorption, Optical design, Electroluminescent displays

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Proceedings Article | 8 March 2014 Paper

Radiative and nonradiative decay of excitons in GaN nanowires

Christian Hauswald, Timur Flissikowski, Holger Grahn, Lutz Geelhaar, Henning Riechert, Oliver Brandt

Proceedings Volume 8986, 89860V (2014) https://doi.org/10.1117/12.2039082

KEYWORDS: Excitons, Gallium nitride, Picosecond phenomena, Photomicroscopy, Solids, Statistical analysis, Spectroscopy, Streak cameras, Data modeling, Nanowires

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Proceedings Article | 15 July 2010 Paper

Toward a compact THz local oscillator based on a quantum-cascade laser

H. Richter, M. Greiner-Baer, S. Pavlov, A. Semenov, M. Wienold, L. Schrottke, M. Giehler, R. Hey, H. Grahn, H.-W. Hübers

Proceedings Volume 7741, 774111 (2010) https://doi.org/10.1117/12.856917

KEYWORDS: Quantum cascade lasers, Terahertz radiation, Absorption, Spectroscopy, Astronomy, Oscillators, Molecular spectroscopy, Sensors, Copper, Molecules

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Proceedings Article | 11 May 2004 Paper

Physical processes and lasing properties of GaAs/(Al,Ga)As quantum-cascade structures and lasers

Holger Grahn

Proceedings Volume 5365, (2004) https://doi.org/10.1117/12.531674

KEYWORDS: Quantum cascade lasers, Doping, Absorption, Waveguides, Gallium, Laser damage threshold, Quantum wells, Solids, Excitons, Signal detection

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Proceedings Article | 20 April 1998 Paper

Identification of electron-hole transitions in short-period GaAs/AlAs superlattices by time-resolved photoluminescence

Vladimir Litovchenko, Dmytro Korbutyak, Sergiy Krylyuk, Holger Grahn, R. Klann, Klaus Ploog

Proceedings Volume 3359, (1998) https://doi.org/10.1117/12.306211

KEYWORDS: Stereolithography, Excitons, Superlattices, Quantum wells, Luminescence, Picosecond phenomena, Gallium arsenide, Electrons, Time resolved spectroscopy, Spectroscopy

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Proceedings Article | 3 November 1995 Paper

Application of the polarized photoluminescence method to the characterization of superlattice corrugations

Vladimir Litovchenko, Dmytro Korbutyak, Sergiy Krylyuk, Yurii Kryuchenko, V. Sugakov, Holger Grahn, Klaus Ploog

Proceedings Volume 2648, (1995) https://doi.org/10.1117/12.226183

KEYWORDS: Excitons, Polarization, Superlattices, Interfaces, Luminescence, Quantum wells, Stereolithography, Gallium arsenide, Wave propagation, Radio propagation

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Unique polarization properties of the exciton luminescence in semiconductor superlattices (SL) are the subject of a great current interest. Polarization effects in SLs may be caused by different mechanisms, such as formation of twodimensional subbands, exciton localization, existence ofthe microreliefat heterointerfaces, etc. [1-3]. We have investigated the polarization properties ofthe photoluxriinescence (PL) spectra of GaAs-AlAs superlatlices in a wide range ofquantum well and barrier widths. The sample parameters, i.e. well width d, the barrier width d, the number ofperiods N, the type of SL, and the corresponding degrees oflinear polarization are listed in table 1. In both direct-gap SLs-I (d <4 n.tn) and indirect-gap SLs-II (d <4 nm) the polarization of PL lines is caused by the splitting of heavy and light hole bands and the anisotropy ofheavy holes, but this effect alone cannot explain the polarization ofthe luminescence irradiated in the direction normal to the surface of investigated structure (i.e. at small detection angles). For SLs-I we have observed rather large linear polarization PL=(I-I)/(I.,+IS), where I and I are the intensifies of exciton luminescence polarized in the plane ofdetection and normal to it. In this case polanzation may achieve values ofabout 20%. In SLs-II with narrow wells photoluminescence is caused by indirect exciton transitions between X-electrons of AlAs and r -heavy holes of GaAs. It is known that such excitons are localized at interface inhomogeneities [4]. The value of P1 for these SLs is lower than for the SLs-I (L=5-1° %). We have studied the dependence ofpolarization degree on the angle of PL detection for SL—II with the well width 3.4 run and barrier width 4.0 nm for two cases of crystallographic directions ([1 10] and [1 1 0]). The parameters of such samples were close to the case when direct —indirect crossover is observed. As a consequence of this fact two lines were observed in PL spectrum, one of which is associated with indirect recombination of X-electrons and another with direct recombination of F-electrons. r-Iine is almost unpolarized (L'1)' while X-line is characterized by rather large polarization degree (up to 10%), which decreases with the increase ofdetection angle and changes its sign (for small detection angles) with the 90°-turn of the sample around the axis normal to its surface. This anomalous behavior requires an adequate theoretical explanation. From our point ofview such explanation may be given if the existence of heterointerface corrugations in superlattice is taken into account. At the same time the fact ofsmall broadening of observed PL line (substantially lower than possible line splitting due to monolayer fluctuations in quantum well width) proves a strong correlation between such corrugations on both sides ofeach quantum well, i.e. the shape of corrugations in heterointerfaces in superlattice is determined by the shape of corrugations on the surface ofthe substrate.

Proceedings Article | 26 May 1994 Paper

Electroreflectance line-shape analysis for coupled GaAs-AlAs superlattices in strong electric fields

Udo Behn, Holger Grahn, Klaus Ploog

Proceedings Volume 2141, (1994) https://doi.org/10.1117/12.176852

KEYWORDS: Superlattices, Dielectrics, Absorption, Stereolithography, Reflectivity, Modulation, Quantum wells, Gallium arsenide, Spectroscopy, Refractive index

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Proceedings Article | 6 May 1994 Paper

Resonant tunneling in unipolar triple-barrier structures investigated by time-resolved photoluminescence

Chris Van Hoof, Jan Genoe, Gustaaf Borghs, Dietrich Bertram, Herbert Lage, Wolfgang Ruehle, Holger Grahn

Proceedings Volume 2142, (1994) https://doi.org/10.1117/12.175904

KEYWORDS: Quantum wells, Luminescence, Gallium arsenide, Electron transport, Picosecond phenomena, Signal detection, Chlorine, Solids, Signal processing, Diodes

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Proceedings Article | 4 June 1993 Paper

Tip/sample interactions, contrast, and near-field microscopy of biological and solid-state samples

Steven Smith, Eric Monson, Greg Merritt, Weihong Tan, D. Birnbaum, Zhong-You Shi, Bjorn Thorsrud, C. Harris, Holger Grahn, Klaus Ploog, Roberto Merlin, Bradford Orr, John Langmore, Raoul Kopelman

Proceedings Volume 1855, (1993) https://doi.org/10.1117/12.146366

KEYWORDS: Near field scanning optical microscopy, Gold, Luminescence, Particles, Near field, Transmission electron microscopy, Scanning probe microscopy, Liver, Spatial resolution, Sensors

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Proceedings Article | 3 September 1992 Paper

Carrier injection into higher subbands by resonant tunneling in superlattices

Holger Grahn, Wolfgang Ruehle, Klaus Ploog

Proceedings Volume 1675, (1992) https://doi.org/10.1117/12.137612

KEYWORDS: Superlattices, Quantum wells, Oscillators, Luminescence, Scattering, Physics, Spectroscopy, Picosecond phenomena, Phonons, Gallium arsenide

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Proceedings Article | 3 September 1992 Paper

Transition from miniband to Wannier-Stark states in GaAs-AlAs superlattices

Klaus Schmidt, Alessandra D'Intino, Norbert Linder, M. Tuna, Gottfried Doehler, Holger Grahn, Klaus Ploog, K. Kawashima, Kenzo Fujiwara

Proceedings Volume 1675, (1992) https://doi.org/10.1117/12.137619

KEYWORDS: Absorption, Electrons, Stereolithography, Quantum wells, Superlattices, Modulation, Double positive medium, Physics, Spectroscopy, Gallium arsenide

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Proceedings Article | 3 September 1992 Paper

Interaction of Wannier-Stark ladders in GaAs-AlAs superlattices observed by electroreflectance

Udo Behn, Holger Grahn, Harald Schneider, Klaus Ploog

Proceedings Volume 1675, (1992) https://doi.org/10.1117/12.137620

KEYWORDS: Superlattices, Quantum wells, Physics, Spectroscopy, Modulation, Dielectrics, Oscillators, Temperature metrology, Phase shift keying, Solids

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Proceedings Article | 1 October 1990 Paper

Optical detection of resonant tunneling in GaAs/AlAs superlattices

Harald Schneider, Holger Grahn, K. Klitzing, Klaus Ploog

Proceedings Volume 1283, (1990) https://doi.org/10.1117/12.20723

KEYWORDS: Stereolithography, Superlattices, Physics, Luminescence, Spectroscopy, Gallium arsenide, Electron transport, Absorption, Diodes, Time resolved spectroscopy

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Proceedings Article | 1 October 1990 Paper

Miniband transport in GaAs-AlAs superlattices

Holger Grahn, Harald Schneider, Klaus von Klitzing, Klaus Ploog

Proceedings Volume 1283, (1990) https://doi.org/10.1117/12.20728

KEYWORDS: Superlattices, Scattering, Physics, Temperature metrology, Semiconductors, Statistical modeling, Solids, Nanoelectromechanical systems, Diodes, Semiconductor lasers

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Showing 5 of 15 publications

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