TY - JOUR A1 - Streubühr, C. A1 - Kalus, Annika A1 - Zhou, Ping A1 - Ligges, Manuel A1 - Hanisch-Blicharski, Anja A1 - Kammler, Martin A1 - Bovensiepen, U. A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. T1 - Comparing ultrafast surface and bulk heating using time-resolved electron diffraction JF - Applied Physics Letters N2 - From measurements of the transient Debye-Waller effect in Bismuth, we determine the buildup time of the random atomic motion resulting from the electronic relaxation after short pulse laser excitation. The surface sensitive reflection high energy electron diffraction and transmission electron diffraction yield a time constant of about 12 ps and 3 ps, respectively. The different energy transfer rates indicate relatively weak coupling between bulk and surface vibrational modes. (C) 2014 AIP Publishing LLC. Y1 - 2014 U6 - https://doi.org/10.1063/1.4872055 VL - 104 SP - 1 EP - 3 PB - American Institute of Physics ER - TY - CHAP A1 - Shymanovich, Uladzimir A1 - Nicoul, Matthieu A1 - Lu, Wei A1 - Tarasevitch, A. A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Sokolowski-Tinten, Klaus A1 - Phipps, Claude T1 - Coherent acoustic and optical phonons in laser-excited solids studied by ultrafast time-resolved X-ray diffraction T2 - AIP Conference Proceedings N2 - We apply ultrafast time‐resolved X‐ray diffraction to directly study coherent acoustic and optical phonons in laser‐excited materials. In Au the ps acoustic response has been investigated with the particular goal to clarify the interplay of electronic and thermal pressure contributions. In Bi the extreme softening of the coherently excited A 1 g optical phonon presents strong indication that upon intense laser‐excitation the Peierls‐transition which determines the equilibrium structure of Bi can be reversed. In FeRh we studied the lattice response after a fast laser‐induced anti‐ferromagnetic to ferromagnetic phase transition. Y1 - 2010 U6 - https://doi.org/10.1063/1.3507146 IS - 1 SP - 558 EP - 566 PB - AIP ER - TY - JOUR A1 - Payer, Thomas A1 - Klein, C. A1 - Acet, M. A1 - Ney, V. A1 - Kammler, Martin A1 - Meyer zu Heringdorf, Frank-Joachim A1 - Horn-von Hoegen, Michael T1 - High-quality epitaxial Bi(111) films on Si(111) by isochronal annealing JF - Thin Solid Films N2 - Bi(111) films grown on Si(111) at room temperature show a significantly higher roughness compared to Bi films grown on Si(100) utilizing a kinetic pathway based on a low-temperature process. Isochronal annealing steps of 3 min duration each with temperatures up to 200 °C cause a relaxation of the Bi films' lattice parameter toward the Bi bulk value and yield an atomically flat Bi surface. Driving force for the relaxation and surface reordering is the magic mismatch of 11 Bi atoms to 13 Si atoms that emerges at annealing temperatures above 150 °C and reduces the remaining strain to less than 0.2%. KW - Epitaxy KW - Strain KW - Annealing KW - Bismuth KW - Silicon Y1 - 2012 U6 - https://doi.org/10.1016/j.tsf.2012.06.004 VL - 520 IS - 23 SP - 6905 EP - 6908 PB - Elsevier ER - TY - CHAP A1 - Zhou, Ping A1 - Streubühr, C. A1 - Kalus, Annika A1 - Frigge, Tim A1 - Wall, S. A1 - Hanisch-Blicharski, Anja A1 - Kammler, Martin A1 - Ligges, Manuel A1 - Bovensiepen, U. A1 - von der Linde, D. A1 - Horn-von Hoegen, Michael T1 - Ultrafast time resolved reflection high energy electron diffraction with tilted pump pulse fronts T2 - EPJ Web of Conferences - XVIIIth International Conference on Ultrafast Phenomena N2 - We present time-resolved RHEED from a laser excited Pb(111) surface using a pulse front tilter for the compensation of the velocity mismatch of electrons and light. The laser pulses with tilted fronts were characterized by a spatially resolving cross correlator. The response of the surface upon excitation was observed to be less than 2 ps. Y1 - 2013 U6 - https://doi.org/10.1051/epjconf/20134110016 VL - 41 PB - EPJ ER - TY - CHAP A1 - Lu, Wei A1 - Nicoul, Matthieu A1 - Shymanovich, Uladzimir A1 - Tarasevitch, A. A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Sokolowski-Tinten, Klaus T1 - Transient reversal of a Peierls-transition: Extreme phonon softening in laser-excited Bismuth T2 - International Conference on Ultrafast Phenomena, Snowmass N2 - Laser-excited coherent optical phonons in Bismuth were investigated using time-resolved X-ray diffraction. The observed extreme softening of the excited A1g-mode presents strong indication that the Peierls-distortion defining the equilibrium structure of Bismuth is transiently reversed. Y1 - 2010 U6 - https://doi.org/10.1364/UP.2010.ME41 IS - ME41 PB - Optica Publishing Group ER - TY - JOUR A1 - Portavoce, A. A1 - Kammler, Martin A1 - Hull, Robert A1 - Reuter, Mark C. A1 - Copel, M. A1 - Ross, Frances M. T1 - Growth of nanostructures by locally modified surface reactivity JF - Materials Science in Semiconductor Processing N2 - The chemical vapor deposition (CVD) of Si and Ge on Si(0 0 1) substrates covered by 1 monolayer of Ga has been studied. Ga modifies surface reactivity and surface atom mobility. We show that islanding occurs during Ga-mediated CVD even in the absence of strain, allowing for the formation of islands without a wetting layer or with a thinner wetting layer. The morphology of the grown layer is highly dependent on kinetic parameters, i.e. growth temperature and growth pressure, that control Si and Ge deposition and Ga desorption. Si Ga-mediated CVD promotes the formation of self-assembled epitaxial Si islands exhibiting {1 1 3} facets. Ge islands grown by Ga-mediated CVD present reduced lateral sizes and an increased surface density compared to non Ga-mediated CVD. The growth morphology (particularly island size and density) can be understood by considering a qualitative model in which atoms are deposited only on sites whose dangling bonds are not passivated by Ga. We suggest that modification of surface reactivity during surfactant-mediated CVD can thus provide a new degree of freedom for quantum dot fabrication. KW - UHV TEM KW - UHV CVD KW - Epitaxial growth KW - Si KW - Ge KW - Surfactant Ga Y1 - 2009 U6 - https://doi.org/10.1016/j.mssp.2009.07.001 VL - 12 IS - 1-2 SP - 25 EP - 30 PB - Elsevier ER - TY - JOUR A1 - Portavoce, A. A1 - Kammler, Martin A1 - Hull, Robert A1 - Reuter, Mark C. A1 - Ross, Frances M. T1 - Mechanism of the nanoscale localization of Ge quantum dot nucleation on focused ion beam templated Si(001) surfaces JF - Nanotechnology N2 - We investigate the fundamental mechanism by which self-assembled Ge islands can be nucleated at specific sites on Si(001) using ultra-low-dose focused ion beam (FIB) pre-patterning. Island nucleation is controlled by a nanotopography that forms after the implantation of Ga ions during subsequent thermal annealing of the substrate. This nanotopography evolves during the annealing stage, changing from a nanoscale annular depression associated with each focused ion beam spot to a nanoscale pit, and eventually disappearing (planarizing). The correspondence of Ge quantum dot nucleation sites to the focused ion beam features requires a growth surface upon which the nanotopography is preserved. A further key observation is that the Ge wetting layer thickness is reduced in patterned regions, allowing the formation of islands on the templated regions without nucleation elsewhere. These results provide routes to the greatly enhanced design and control of quantum dot distributions and dimensions. Y1 - 2006 U6 - https://doi.org/10.1088/0957-4484/17/17/028 VL - 17 IS - 17 SP - 4451 EP - 4455 PB - IOP ER - TY - JOUR A1 - Ross, Frances M. A1 - Kammler, Martin A1 - Reuter, Mark C. A1 - Hull, Robert T1 - In-situ observations of self-assembled island nucleation on patterned substrates JF - Philosophical Magazine N2 - We compare in-situ electron microscopy observations of Ge island growth on Si surfaces modulated by different techniques. Si(001) substrates were patterned either using a focused Ga ion beam or lithographically to produce similar feature sizes. In the case of the focused-ion-beam patterned substrates, chemical or strain effects caused by low Ga doses control the positions at which islands nucleate. Nucleation on topographically modulated substrates, with the pattern produced either by high-dose sputtering or lithographically, is controlled by the nature of the side walls of topographic features. The two patterning approaches have different benefits in creating arrays of islands for device applications. Y1 - 2004 U6 - https://doi.org/10.1080/14786430410001671430 VL - 84 IS - 25-26 SP - 2687 EP - 2702 PB - Taylor & Francis ER - TY - JOUR A1 - Menzel, Andreas A1 - Conrad, E. H. A1 - Tringides, Michael C. A1 - Kammler, Martin A1 - Horn- von Hoegen, Michael T1 - Finite collection time effects in autocovariance function measurements JF - Journal of Applied Physics N2 - In this paper we discuss how finite data sets influence experimental measurements of the autocovariance function. Autocovariance estimators are biased, meaning that the expectation value for any measured autocovariance function is not identical to the actual autocovariance function. In this work we show that the measured autocovariance function for a finite length time series must become negative for some lag times. We derive analytic corrections to these finite time errors for different types of correlated random sequences. Our results explain the apparent anticorrelated noise observed in experimental observations. Y1 - 2003 U6 - https://doi.org/10.1063/1.1537466 VL - 93 IS - 4 SP - 2229 EP - 2235 PB - AIP Publishing ER - TY - JOUR A1 - Kammler, Martin A1 - Hull, Robert A1 - Reuter, Mark C. A1 - Ross, Frances M. T1 - Lateral control of self-assembled island nucleation by focused-ion-beam micropatterning JF - Applied Physics Letters N2 - We demonstrate that the nucleation sites of nanoscale, self-assembled Ge islands on Si(001) can be controlled by patterning the Si surface in situ with a focused ion beam. At low doses of 6000 Ga+ ions per <100 nm spot, the selective growth is achieved without modifying the initial surface topography. At larger doses, topographic effects produced by sputtering and redeposition control the selective nucleation sites. Islands grown on irradiated spots are smaller with higher aspect ratio than islands grown on clean Si(001), suggesting a strong surfactant effect of Ga. Y1 - 2003 U6 - https://doi.org/10.1063/1.1542680 VL - 82 IS - 7 SP - 1093 EP - 1095 ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Shymanovich, Uladzimir A1 - Nicoul, Matthieu A1 - Cavalleri, Andrea A1 - Tarasevitch, A. A1 - Horn-von Hoegen, Michael A1 - Kammler, Martin A1 - von der Linde, D. T1 - Ultrafast X-ray diffraction JF - Ultrafast Phenomena XIV N2 - In the last few years the generation of femtosecond pulses in the X-ray regime has become possible. These ultrashort X-ray pulses have enabled femtosecond time- resolution to be extended to X-rays. Y1 - 2005 U6 - https://doi.org/10.1007/3-540-27213-5_53 VL - 79 SP - 170 EP - 174 PB - Springer ER - TY - JOUR A1 - Kammler, Martin A1 - Hull, Robert A1 - Portavoce, A. A1 - Reuter, Mark C. A1 - Ross, Frances M. T1 - In-Situ Focused Ion Beam Micropatterning of Ge Islands JF - Microscopy and Microanalysis Y1 - 2003 U6 - https://doi.org/10.1017/S1431927603441214 VL - 9 IS - S02 SP - 132 EP - 134 PB - Microscopy Society of America ER - TY - JOUR A1 - Fritz, D. M. A1 - Reis, D. A. A1 - Adams, B. A1 - Akre, R. A. A1 - Arthur, J. A1 - Blome, Christian A1 - Bucksbaum, P. H. A1 - Cavalieri, A. L. A1 - Engemann, S. A1 - Fahy, S. A1 - Falcone, R. W. A1 - Fuoss, P. H. A1 - Gaffney, K. J. A1 - George, M. J. A1 - Hajdu, J. A1 - Hertlein, M. P. A1 - Hillyard, P. B. A1 - Horn-von Hoegen, Michael A1 - Kammler, Martin A1 - Kaspar, J. A1 - Kienberger, R. A1 - Krejcik, P. A1 - Lee, S. H. A1 - Lindenberg, A. M. A1 - McFarland, B. A1 - Meyer, D. A1 - Montagne, T. A1 - Murray, E. D. A1 - Nelson, A. J. A1 - Nicoul, Matthieu A1 - Pahl, R. A1 - Rudati, J. A1 - Schlarb, H. A1 - Siddons, D. P. A1 - Sokolowski-Tinten, Klaus A1 - Tschentscher, Th A1 - von der Linde, D. A1 - Hastings, J. B. T1 - Ultrafast bond softening in bismuth: mapping a solid's interatomic potential with X-rays JF - Science N2 - Intense femtosecond laser excitation can produce transient states of matter that would otherwise be inaccessible to laboratory investigation. At high excitation densities, the interatomic forces that bind solids and determine many of their properties can be substantially altered. Here, we present the detailed mapping of the carrier density-dependent interatomic potential of bismuth approaching a solid-solid phase transition. Our experiments combine stroboscopic techniques that use a high-brightness linear electron accelerator-based x-ray source with pulse-by-pulse timing reconstruction for femtosecond resolution, allowing quantitative characterization of the interatomic potential energy surface of the highly excited solid. Y1 - 2007 U6 - https://doi.org/10.1126/science.1135009 VL - 315 IS - 5812 SP - 633 EP - 636 PB - AAAS ER - TY - CHAP A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Shymanovich, Uladzimir A1 - Nicoul, Matthieu A1 - Cavalleri, Andrea A1 - Tarasevitch, A. A1 - Horn-von Hoegen, Michael A1 - Kammler, Martin A1 - von der Linde, Dietrich ED - Kobayashi, Tetsuro T1 - Ultrafast X-ray diffraction T2 - Ultrafast Phenomena XIV N2 - In the last few years the generation of femtosecond pulses in the X-ray regime has become possible. These ultrashort X-ray pulses have enabled femtosecond time- resolution to be extended to X-rays. Y1 - 2004 SN - 978-3-540-27213-7 U6 - https://doi.org/10.1007/3-540-27213-5_53 VL - 79 SP - 170 EP - 174 PB - Springer CY - Berlin, Heidelberg ER - TY - JOUR A1 - Kammler, Martin A1 - Horn- von Hoegen, Michael A1 - Voss, N. A1 - Tringides, Michael C. A1 - Menzel, Andreas A1 - Conrad, E. H. T1 - Si(001) step dynamics: A temporal low-energy electron diffraction study JF - Physical Review B N2 - We present equilibrium measurements of the dynamics of steps on Si(001) using temporal electron-diffraction spectroscopy. Activation energies and the rate limiting kinetics are identified for 950K<~T<~1130K. Unlike previous studies at higher temperatures, we can exclude evaporation and condensation of atoms or dimers from the step edges as the rate limiting process in this temperature regime. The possible reason for this difference is discussed in terms of a crossover from different rate-limiting kinetics. Y1 - 2002 U6 - https://doi.org/10.1103/PhysRevB.65.075312 VL - 65 IS - 7 PB - APS ER - TY - JOUR A1 - Krenzer, Boris A1 - Hanisch-Blicharski, Anja A1 - Schneider, Paul A1 - Payer, Thomas A1 - Möllenbeck, Simone A1 - Osmani, O. A1 - Kammler, Martin A1 - Meyer, R. A1 - Horn-von Hoegen, Michael T1 - Phonon confinement effects in ultrathin epitaxial bismuth films on silicon studied by time-resolved electron diffraction JF - Physical Review B N2 - The transient temperature evolution of ultrathin bismuth films, epitaxially grown on a silicon single crystal, upon femtosecond laser excitation is studied by time-resolved electron diffraction. The exponential decay of the film temperature is explained by phonon reflection at the interface, which results in a strongly reduced thermal conduction in the cross plane of the layered system. The thermal boundary conductance is found to be as low as 1273 W/(K cm2). Model calculations, including phonon confinement effects, explain the linear relationship between the observed film-temperature decay constant and the film thickness. Even for 2.5 nm thin films the phonon transmission probability across the interface is given by bulk properties. Our simulations show that phonon confinement effects are negligible for bismuth-film thicknesses larger than 1 nm. Y1 - 2009 U6 - https://doi.org/10.1103/PhysRevB.80.024307 VL - 80 IS - 2 PB - APS ER - TY - JOUR A1 - Klein, C. A1 - Nabbefeld, T. A1 - Hattab, H. A1 - Meyer, D. A1 - Jnawali, G. A1 - Kammler, Martin A1 - Meyer zu Heringdorf, Frank-Joachim A1 - Golla-Franz, A. A1 - Müller, B. H. A1 - Schmidt, Thomas A1 - Henzler, M. A1 - Horn-von Hoegen, Michael T1 - Lost in reciprocal space? Determination of the scattering condition in spot profile analysis low-energy electron diffraction JF - Review of scientific instruments N2 - The precise knowledge of the diffraction condition, i.e., the angle of incidence and electron energy, is crucial for the study of surface morphology through spot profile analysis low-energy electron diffraction (LEED). We demonstrate four different procedures to determine the diffraction condition: employing the distortion of the LEED pattern under large angles of incidence, the layer-by-layer growth oscillations during homoepitaxial growth, a G(S) analysis of a rough surface, and the intersection of facet rods with 3D Bragg conditions. Y1 - 2011 U6 - https://doi.org/10.1063/1.3554305 VL - 82 IS - 3 PB - American Institute of Physics ER - TY - JOUR A1 - Schmidt, Thomas A1 - Kröger, Roland A1 - Clausen, T. A1 - Falta, J. A1 - Janzen, Andreas A1 - Kammler, Martin A1 - Kury, P. A1 - Zahl, P. A1 - Horn-von Hoegen, Michael T1 - Surfactant-mediated epitaxy of Ge on Si(111): Beyond the surface JF - Applied Physics Letters N2 - For a characterization of interface and “bulk” properties of Ge films grown on Si(111) by Sb surfactant-mediated epitaxy, grazing incidence x-ray diffraction and transmission electron microscopy have been used. The interface roughness, defect structure, and strain state have been investigated in dependence of film thickness and growth temperature. For all growth parameters, atomically smooth interfaces are observed. For thin Ge layers, about 75% of the strain induced by the lattice mismatch is relaxed by misfit dislocations at the Ge/Si interface. Only a slight increase of the degree of relaxation is found for thicker films. At growth temperatures below about 600 °C, the formation of twins is observed, which can be avoided at higher temperatures. Y1 - 2005 U6 - https://doi.org/10.1063/1.1882760 VL - 86 IS - 11 PB - AIP ER - TY - JOUR A1 - Frigge, Tim A1 - Wall, S. A1 - Krenzer, Boris A1 - Wippermann, St. A1 - Sanna, Simone A1 - Klasing, Friedrich A1 - Hanisch-Blicharski, Anja A1 - Kammler, Martin A1 - Schmidt, Wolf Gero A1 - Horn-von Hoegen, Michael T1 - Abstract - A Reply to the Comment by H. Shim et al. JF - Physical review letters Y1 - 2013 U6 - https://doi.org/10.1103/PhysRevLett.111.149602 VL - 111 IS - 14 PB - American Physical Society ER - TY - JOUR A1 - Chee, See Wee A1 - Kammler, Martin A1 - Graham, Jeremy A1 - Ross, Frances M. A1 - Hull, Robert T1 - Direct Imaging of Microstructural Changes in Si Induced by FIB-Patterning with Si ++ and Ga + Ions JF - Microscopy and Microanalysis Y1 - 2011 U6 - https://doi.org/10.1017/S1431927611004156 VL - 17 IS - S2 SP - 656 EP - 657 PB - Cambridge University Press ER - TY - JOUR A1 - Schwarz, Tobias A1 - Pastötter, Angelina A1 - Tran, T. H. A1 - Schlosser, Marc A1 - Kaulen, Corinna A1 - Lechner, Alfred A1 - Slabon, A. A1 - Kammler, Martin T1 - Effect of temperature on the growth of Cupric and Cuprous Nanoparticles in a wet chemical synthesis JF - Materials Letters N2 - Cuprous oxide (Cu2O) and cupric oxide (CuO) particles were synthesized using a wet chemical surfactant free method at different synthesis temperatures from 25 °C to 60 °C. Morphology, size, and chemical composition of the prepared Cu2O particles were analyzed by FESEM, PXRD, and UV-vis. We discovered that the chemical composition of the Cu2O particles remained unaffected by the synthesis temperature. However, morphology and size of the particles showed a strong temperature dependency. This could be attributed to the temperature induced formation of CuO species from the copper hydroxide (Cu(OH)2) precursor which also functions as copper precursor for the Cu2O particle growth. The cupric oxide species was determined to be the main cause for the formation of micrometer sized particles, whereas with the Cu(OH)2 precursor species for the Cu2O particles nanocubes with smaller edge lengths as well as octahedrons were obtained. KW - Crystal structure KW - Crystal growth KW - Nanoparticle KW - Copper oxide Y1 - 2025 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:898-opus4-79279 VL - 381 PB - Springer Nature ER - TY - JOUR A1 - Wolfgramm, Alex A1 - Abb, Valerius A1 - Samp, Artur A1 - Samp, Rafal A1 - Hoffmann, Jens Christoph A1 - Müller, Rainer A1 - Kammler, Martin T1 - Structural and functional evolution of HKUST-1 nanoparticles induced by ball milling JF - Next Materials N2 - In this study, the effect of post-synthetic ball milling on the structural and functional properties of as-synthesized nanoparticles of the copper-based metal-organic framework (MOF) HKUST-1 was investigated for the first time. Nanoparticles were synthesized using sodium formate as a capping agent. The crystalline particles were subjected to a controlled ball milling process, which induced significant structural changes. Powder X-ray diffraction (PXRD) revealed a reduction in crystallite size from 91 nm to 21 nm and the introduction of microstrain, partially disrupting the MOF's long-range crystalline order, as evidenced by peak broadening and the diminished intensity of high-angle reflections. Particle morphology pre- and post-milling was further studied with scanning electron microscopy (SEM) imaging, verifying a narrow particle size distribution of ± 22 nm after milling. Fourier-transform infrared spectroscopy (FTIR) indicated protonation of carboxylate groups in the larger pores of the framework, likely due to moisture incorporation during milling. Brunauer-Emmett-Teller (BET) surface area analysis showed a substantial decrease in specific surface area from 521 m²/g to 226 m²/g, suggesting a partial collapse of the porous framework. We discuss the applicability of ball milling as a versatile means of post-synthetic approach to reduce MOF particle sizes, a key element in the preparation of MOF-based thin films using inks or polymers. KW - Ball milling KW - Copper-based metal-organic framework KW - HKUST-1 KW - Nitrogen adsorption Y1 - 2026 U6 - https://doi.org/10.1016/j.nxmate.2025.101544 N1 - Corresponding author der OTH Regensburg: Alex Wolfgramm VL - 10 PB - Elsevier ER -