TY - JOUR A1 - Peter, Daniel A1 - Dalmer, Michael A1 - Lechner, Alfred A1 - Gigler, Alexander M. A1 - Stark, Robert W. A1 - Bensch, Wolfgang T1 - Measurement of the mechanical stability of semiconductor line structures in drying liquids with application to pattern collapse JF - Journal of Micromechanics and Microengineering N2 - Enhanced particle removal processes in wet cleaning as well as drying processes of semiconductor wafers can cause significant lateral forces on surface structures. These forces, however, must not exceed the mechanical stability of structures on the wafer. Thus, a mechanical fracture test was used to assess the lateral mechanical stability of polysilicon line structures in relevant process liquids. The mechanical test was based on nanomanipulation with an atomic force microscope. Compared to fracture tests in air, data acquired in liquid isopropanol revealed a stabilizing effect. The differences in fracture forces can be attributed to a stress corrosion process on the surface. The size of the generated damage was influenced by the viscosity of the surrounding media. Y1 - 2011 U6 - https://doi.org/10.1088/0960-1317/21/2/025001 VL - 21 IS - 2 PB - IOP Science ER - TY - CHAP A1 - Peter, Daniel A1 - Dalmer, Michael A1 - Lotnyk, Andriy A1 - Kienle, Lorenz A1 - Lechner, Alfred A1 - Bensch, Wolfgang T1 - Solid bridging during pattern collapse (stiction) studied on silicon nanoparticles T2 - MRS Online Proceedings Library N2 - The high surface to volume ratio of nanoparticles allows a detailed experimental study of the surface phenomena associated with solid bridging. Besides bulk analyses, the local view on the structure and composition via HRTEM is particularly essential. 50 nm core shell particles consisting of a silicon (Si) core and a SiO2 shell were used as model system to understand surface phenomena appearing for Si-based nanostructures. Evaporative drying from de-ionized water shows the most significant bridging effect based on SiO2. There is only a localized deposition of oxides between the particles during the drying process and no overall oxidation. For the deposition material, silicates are the most likely candidates. Y1 - 2011 U6 - https://doi.org/10.1557/opl.2011.397 VL - 1299 SP - 191 EP - 196 PB - Springer Nature ER - TY - JOUR A1 - Peter, Daniel A1 - Holsteyns, Frank A1 - Dalmer, Michael A1 - Kruwinus, Hans A1 - Lechner, Alfred A1 - Bensch, Wolfgang T1 - A Study on the Structure Collapse Mechanisms for High Aspect Ratio Structures with Application to Clean Processing JF - ECS Meeting Abstracts Y1 - 2009 U6 - https://doi.org/10.1149/MA2009-02/24/2084 VL - MA2009-02 IS - 24 PB - IOP Science ER - TY - INPR A1 - Schwarz, Tobias A1 - Pastötter, Angelina A1 - Tran, Trung A1 - Schlosser, Marc A1 - Kaulen, Corinna A1 - Lechner, Alfred A1 - Kammler, Martin A1 - Slabon, Adam T1 - Effect of Temperature on the Growth of Cu(I)O Nanocubes: The Impact of the Copper Precursor Species T2 - SSRN N2 - Cuprous oxide (Cu2O) nanoparticles 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 nanoparticles were analyzed by SEM, PXRD, and ATR-IR. We discovered that the chemical composition of the Cu2O nanoparticles remained unaffected by the synthesis temperature. However, morphology and size of the nanoparticles showed a strong temperature dependency. This could be attributed to the temperature induced formation of cupric oxide (CuO) species from the copper hydroxide (Cu(OH)2 ) precursor which also functions as copper precursor for the Cu2O nanoparticle 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 nanoparticles nanocubes with smaller edge lengths as well as octahedrons were obtained. KW - nanoparticle KW - Copper oxide KW - crystal growth KW - Crystal structure Y1 - 2024 U6 - https://doi.org/10.2139/ssrn.4909639 PB - Elsevier ER - TY - JOUR A1 - Peter, Daniel A1 - Dalmer, Michael A1 - Lechner, Alfred A1 - Gigler, Alexander M. A1 - Stark, Robert W. A1 - Bensch, Wolfgang T1 - The influence of liquid media on the fracture strength of polysilicon nanostructures JF - Solid State Phenomena N2 - The mechanical stability of nanostructures depends on the surrounding medium. Their stability was probed by lateral force microscopy in liquid media. Previously reported data on water and isopropanol showed an increase in the fracture strength for the latter. Further tests with other alcohols (ethanol, 1-butanol) also showed an increasing strength. The interface between the liquid and the surface is the decisive factor for the influence of the media. When altering the interface with a cationic surfactant or a self-assembled monolayer, an increase of the fracture force by 100 % compared to de-ionized water could be measured. KW - pattern collapse KW - fracture strength KW - damage KW - atomic force microscopy Y1 - 2012 U6 - https://doi.org/10.4028/www.scientific.net/SSP.187.127 VL - 187 SP - 127 EP - 130 PB - Trans Tech Publications ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Dietrich, Clemens A1 - Tarsevitch, Alexander A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich A1 - Cavalleri, Andrea A1 - Kammler, Martin A1 - Uschmann, Ingo A1 - Foerster, Eckhart T1 - Femtosecond X-ray Diffraction Study of Large Amplitude Coherent Optical Phonons in Laser-Excited Bismuth JF - Conference on Lasers and Electro-Optics, 1–6 June 2003, Baltimore, Maryland N2 - Femtosecond time-resolved X-ray diffraction was used to directly study optical phonons in laser-excited Bismuth. A periodic modulation of the diffraction efficiency reveals initially coherent lattice distortions with atomic displacements of nearly 10% of the nearest- neighbor-distance. Y1 - 2003 UR - https://opg.optica.org/abstract.cfm?uri=cleo-2003-CMZ6 PB - Optical Society of America ER - TY - JOUR A1 - Wall, Simone A1 - Krenzer, Boris A1 - Wippermann, Stefan A1 - Sanna, Simone A1 - Klasing, Friedrich A1 - Hanisch-Blicharski, Anja A1 - Kammler, Martin A1 - Schmidt, Wolf Gero A1 - Horn-von Hoegen, Michael T1 - Atomistic picture of charge density wave formation at surfaces JF - Physical review letters N2 - We used ultrafast electron diffraction and density-functional theory calculations to gain insight into the charge density wave (CDW) formation on In/Si(111). Weak excitation by a femtosecond-laser pulse results in the melting of the CDW. The immediate freezing is hindered by a barrier for the motion of atoms during the phase transition: The melted CDW constitutes a long-lived, supercooled phase and is strong evidence for a first-order transition. The freezing into the CDW is triggered by preexisting adsorbates. Starting at these condensation nuclei, the CDW expands one dimensionally on the In/Si(111) surface, with a constant velocity of more than 80 m/s. Y1 - 2012 U6 - https://doi.org/10.1103/PhysRevLett.109.186101 VL - 109 IS - 18 PB - APS ER - TY - JOUR A1 - Frigge, Tim A1 - Kalus, Annika A1 - Klasing, Friedrich A1 - Kammler, Martin A1 - Hanisch-Blicharski, Anja A1 - Horn-von Hoegen, Michael T1 - Nanoscale Heat Transport in Self-Organized Ge Clusters on Si(001) JF - MRS Online Proceedings Library N2 - Ultrafast time resolved transmission electron diffraction (TED) in a reflection geometry was used to study the cooling behavior of self-organized, well defined nanoscale germanium hut and dome clusters on Si(001). The clusters were heated in a pump-probe scheme by fs-laser pulses. The resulting transient temperature rise was then determined from the drop in diffraction intensity caused by the Debye-Waller effect. From a cooling time of τ=177 ps we estimated a strongly reduced heat transfer compared with homogeneous films of equivalent thickness. Y1 - 2012 U6 - https://doi.org/10.1557/opl.2013.148 SP - 45 EP - 50 PB - Springer ER - TY - JOUR A1 - Möllenbeck, Simone A1 - Hanisch-Blicharski, Anja A1 - Schneider, Paul A1 - Ligges, Manuel A1 - Zhou, Ping A1 - Kammler, Martin A1 - Krenzer, Boris A1 - Horn-von Hoegen, Michael T1 - Ultra-fast Time-Resolved Electron Diffraction of Strongly Driven Phase Transitions on Silicon Surfaces JF - MRS Online Proceedings Library N2 - The dynamics of strongly driven phase transitions at surfaces are studied by ultra-fast time-resolved reflection high energy electron diffraction. The surfaces are excited by an intense fs-laser pulse (pump) and probed by an ultra-short electron pulse with variable time delay. The order-disorder phase transition from a c(4 × 2) to a(2 × 1) of the bare Si(001) surface shows a transient decrease of the intensity of the c(4 × 2) spots which recovers on a time scale of a few hundred picoseconds indicating the excitation of the phase transition. On Si(111) a monolayer of Indium induces a (4 × 1) reconstruction which undergoes a Peierls like phase transition to a (8 × "2") reconstruction below 100 K. Upon laser excitation with a fluence of 3.4 mJ/cm 2 at a temperature of 72 K the phase transition was strongly driven. The (8 × "2")-diffraction spots instantaneously disappears, while the intensity of the (4 × 1)-spots increases. This increase of the (4 × 1) spot intensity excludes an explanation by the Debye-Waller-Effect and is evidence for a true structural phase transition at a surface. © 2010 Materials Research Society. Y1 - 2009 U6 - https://doi.org/10.1557/PROC-1230-MM03-09 PB - Springer ER - TY - JOUR A1 - Lu, Wei A1 - Nicoul, Matthieu A1 - Shymanovich, Uladzimir A1 - Tarsevitch, Alexander A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich A1 - Sokolowski-Tinten, Klaus T1 - Extreme Phonon Softening in Laser-excited Bismuth - Towards an Inverse Peierls-transition JF - MRS Online Proceedings Library N2 - Large amplitude coherent optical phonons have been investigated in laser-excited Bismuth by means of femtosecond time-resolved X-ray diffraction. For absorbed laser fluences above 2 mJ/cm2, the experimental data reveal an extreme softening of the excited A1g-mode down to frequencies of about 1 THz, only 1/3 of the unperturbed A1g-frequency. At even stronger excitation the measured diffraction signals no longer exhibit an oscillatory behavior presenting strong indication that upon intense laser-excitation the Peierls-distortion, which defines the equilibrium structure of Bismuth, can be transiently reversed. Y1 - 2009 U6 - https://doi.org/10.1557/PROC-1230-MM03-05 VL - 1230 PB - Springer ER - TY - JOUR A1 - Hanisch-Blicharski, Anja A1 - Krenzer, Boris A1 - Möllenbeck, Simone A1 - Ligges, Manuel A1 - Zhou, Ping A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael T1 - Transient Cooling of Ultrathin Epitaxial Bi(111)-Films on Si(111) Upon Femtosecond Laser Excitation Studied by Ultrafast Reflection High Energy Electron Diffraction JF - MRS Online Proceedings Library N2 - With time resolved ultrafast electron diffraction the cooling process across the interface between a thin film and the underlying substrate was studied after excitation with short laser pulses. From the exponential decay of the surface temperature evolution a thermal boundary conductance of 1430 W/(cm2K) is determined for a 9.7 nm thin Bi(111) film on Si(111). A linear dependence between laser fluence and initial temperature rise was measured for film-thicknesses between 2.5 nm and 34.5 nm. The ratio of initial temperature rise and laser fluence for different film-thicknesses is compared to a model taking multilayer optics into account. The data agree well with this model. Y1 - 2009 U6 - https://doi.org/10.1557/PROC-1172-T04-08 SP - 1 EP - 6 PB - Springer ER - TY - JOUR A1 - Al-Falou, A. A. A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael T1 - Strain state analysis of hetero-epitaxial systems JF - Europhysics Letters N2 - We present a new method to analyze the strain state of epitaxial hetero structures by high-resolution spot profile analysis low-energy electron diffraction. From the variation of the spot profiles with the vertical scattering vector we determine the hetero film roughness, the change of interlayer spacing due to tetragonal distortion, and the variation of the interlayer distance due to partial relaxation of the strained rough film. The practical implementation of this method is simple and can be used to determine the onset of strain-relieving defects during the growth process. Y1 - 2005 U6 - https://doi.org/10.1209/epl/i2004-10399-6 VL - 69 IS - 4 SP - 570 EP - 576 PB - IOP ER - TY - JOUR A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael T1 - Low energy electron diffraction of epitaxial growth of bismuth on Si(111) JF - Surface Science N2 - The epitaxial growth of Bi on Si(1 1 1) studied by spot profile analyzing low energy electron diffraction shows for low coverage rotationally disordered Bi cluster with preferred orientations following the threefold symmetry of the Si substrate. With further deposition the Bi cluster coalesces and the surface orientation changes from the pseudo cubic Bi(1 1 0) surface orientation of the Bi cluster into the hexagonal Bi(1 1 1) surface of the resulting Bi film. KW - Bismuth KW - Epitaxial growth KW - LEED KW - low energy electron diffraction KW - Silicon KW - Structural transition Y1 - 2005 U6 - https://doi.org/10.1016/j.susc.2004.11.033 VL - 576 IS - 1-3 SP - 56 EP - 60 PB - Elsevier ER - TY - CHAP A1 - Siders, C. W. A1 - Cavalleri, Andrea A1 - Tóth, Csaba A1 - Wilson, K. R. A1 - Squier, Jeff A. A1 - Barty, C. P. J. A1 - Kammler, Martin A1 - Sokolowski-Tinten, Klaus A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. T1 - Femtosecond X-ray diffraction of short-pulse irradiated semiconductors T2 - Summaries of Papers Presented at the Lasers and Electro-Optics. CLEO '02. Technical Diges, 24-24 May 2002, Long Beach, CA, USA N2 - Summary form only given, as follow. Ultrafast optical-pump, X-ray diffraction probe experiments are providing new ways to study transient processes including the direct observation of the atomic motion by which many solid-state processes and chemical and biochemical reactions take place. Current table-top-terawatt femtosecond laser systems provide an attractive source of few-hundred femtosecond duration bursts of angstrom-scale X-ray radiation with fluxes comparable to standard rotating anode sources. Their compact size enables time resolved structural dynamics to be studied in the small laboratory with temporal resolution better than typical molecular vibrational periods. Ultrafast structural dynamics in crystalline samples are readily studied with such systems and experiments to be discussed in this talk include ultrafast non-thermal solid-to-liquid transition in thin single-crystal Ge-111 films grown on Si-111 substrates; ultrafast non-thermal solid-to-solid transitions in bulk vanadium dioxide from a low temperature insulating phase to a high temperature metallic phase; and harmonic and anharmonic coherent acoustic dynamics in layered Ge-111/Si-111 and bulk GaAs-111 samples. Future improvements in high-average power short-pulse lasers will enable the study of a wider class of materials such as amorphous solids or liquid-phase dynamics of simple molecules, while proposed 4th generation light sources based upon single-pass X-ray free-electron lasers will permit singleshot structural determination of complex biomolecules. KW - high-speed techniques KW - X-ray diffraction KW - laser beam effects KW - semiconductor materials KW - solid-liquid transformations KW - solid-state phase transformations KW - metal-insulator transition Y1 - 2002 U6 - https://doi.org/10.1109/CLEO.2002.1033997 SP - 297 EP - 298 PB - IEEE ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Blums, Juris A1 - Cavalleri, Andrea A1 - Dietrich, Clemens A1 - Tarasevitch, Alexander A1 - Uschmann, Ingo A1 - Förster, Eckhard A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, Dietrich T1 - Femtosecond X-ray measurement of coherent lattice vibrations near the Lindemann stability limit JF - Nature N2 - The study of phase-transition dynamics in solids beyond a time-averaged kinetic description requires direct measurement of the changes in the atomic configuration along the physical pathways leading to the new phase. The timescale of interest is in the range 10(-14) to 10(-12) s. Until recently, only optical techniques were capable of providing adequate time resolution, albeit with indirect sensitivity to structural arrangement. Ultrafast laser-induced changes of long-range order have recently been directly established for some materials using time-resolved X-ray diffraction. However, the measurement of the atomic displacements within the unit cell, as well as their relationship with the stability limit of a structural phase, has to date remained obscure. Here we report time-resolved X-ray diffraction measurements of the coherent atomic displacement of the lattice atoms in photoexcited bismuth close to a phase transition. Excitation of large-amplitude coherent optical phonons gives rise to a periodic modulation of the X-ray diffraction efficiency. Stronger excitation corresponding to atomic displacements exceeding 10 per cent of the nearest-neighbour distance-near the Lindemann limit-leads to a subsequent loss of long-range order, which is most probably due to melting of the material. Y1 - 2003 U6 - https://doi.org/10.1038/nature01490 VL - 422 IS - 6929 SP - 287 EP - 289 PB - Springer ER - TY - JOUR A1 - Hild, R. A1 - Seifert, C. A1 - Kammler, Martin A1 - Meyer zu Heringdorf, Frank-Joachim A1 - Horn-von Hoegen, Michael A1 - Zhachuk, R.A A1 - Olshanetsky, B.Z T1 - Kinetics of Au induced faceting of vicinal Si(111) JF - Surface Science N2 - Au induced faceting of vicinal Si(1 1 1) has been studied during adsorption at elevated temperature by spot profile analyzing of low energy electron diffraction and after quenching to room temperature by scanning tunneling microscopy. On the surfaces inclined towards five different types of facets form with increasing Au coverage at adsorption temperatures Tads below 800 °C. They are (4 4 3), (7 7 5), (5 5 3), a stepped (2 2 1), and the (3 3 1) facets. Atomic models for the (5 5 3) and (7 7 5) facet planes are proposed on the basis of high resolution STM images. At C we found the formation of an ordered step train which covers the entire surface. With further increasing Au coverage the stepped surface decomposes again into (1 1 1) terraces and step bunches. Driving force is the formation of the Si(1 1 1)-(5×2)–Au reconstruction. KW - Low energy electron diffraction (LEED) KW - Scanning tunneling microscopy KW - Silicon KW - Gold KW - Faceting KW - Adsorption kinetics KW - Step formation and bunching Y1 - 2002 U6 - https://doi.org/10.1016/S0039-6028(02)01666-7 VL - 512 IS - 1-2 SP - 117 EP - 127 PB - Elsevier ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Cavalleri, Andrea A1 - Siders, C. W. A1 - Brown, F. L. H. A1 - Leitner, D. M. A1 - Tóth, Csaba A1 - Squier, Jeff A. A1 - Barty, C. P. J. A1 - Wilson, K. R. A1 - Kammler, Martin T1 - Transient lattice dynamics in fs-laser-excited semiconductors probed by ultrafast X-ray diffraction JF - Journal de Physique IV N2 - A study of lattice dynamics in fs-laser-excited crystalline bulk Ge and Ge/Si-heterostructures, using time-resolved x-ray diffraction, was presented. Fast energy transport deep into the bulk of the material, coherent acoustic phonon dynamics, lattice anharmonicity, and vibrational transport across a buried interfaces were observed. Graphs showing time-dependent shifts of the centroid of the measured rocking curves in the Ge-overlayer and in the Si-substrate for different fluences, were presented. Y1 - 2001 U6 - https://doi.org/10.1051/jp4:2001290 VL - 11 IS - Pr2 SP - 473 EP - 477 PB - EDP ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Cavalleri, Andrea A1 - Siders, C. W. A1 - Brown, F. L. H. A1 - Leitner, D. M. A1 - Tóth, Csaba A1 - Kammler, Martin A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Squier, Jeff A. A1 - Barty, C. P. J. A1 - Wilson, K. R. T1 - Time-resolved x-ray diffraction study of ultrafast acoustic phonon dynamics in Ge/Si-heterostructures JF - Chemical Physics N2 - Using time-resolved x-ray diffraction the ultafast strain dynamics in fs-laserexcited Ge/Si-heterostructures has been studied. A fluence dependent, anharmonic damping of the impulsively generated acoustic phonons and vibrational transport across the buried Ge/Si-interface are observed. Y1 - 2001 U6 - https://doi.org/10.1007/978-3-642-56546-5_81 VL - 66 SP - 281 EP - 283 PB - Springer ER - TY - CHAP A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Dietrich, Clemens A1 - Blums, Juris A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Cavalleri, Andrea A1 - Squier, Jeff A. A1 - Kammler, Martin T1 - Structural dynamics in laser-excited solids investigated with femtosecond x-ray diffraction T2 - 2002 Summaries of Papers Presented at the Quantum Electronics and Laser Science Conference, 19-24 May 2002, Long Beach, CA, USA N2 - Summary form only given. Ultrashort x-ray pulses offer a unique combination of atomic-scale spatial and temporal resolution, which permits direct measurements of structural transients on an ultrafast time scale. Using time-resolved X-ray diffraction with femtosecond, multi-keV X-ray pulses we have studied transient lattice dynamics in optically excited semiconductors. Y1 - 2002 U6 - https://doi.org/10.1109/QELS.2002.1031182 SP - 115 EP - 116 PB - IEEE ER - TY - JOUR A1 - Sokolowski-Tinten, Klaus A1 - Blome, Christian A1 - Dietrich, Clemens A1 - Tarasevitch, A. A1 - Horn-von Hoegen, Michael A1 - von der Linde, D. A1 - Cavalleri, Andrea A1 - Squier, Jeff A. A1 - Kammler, Martin T1 - Femtosecond x-ray measurement of ultrafast melting and large acoustic transients JF - Physical review letters N2 - Time-resolved x-ray diffraction with ultrashort ( approximately 300 fs), multi-keV x-ray pulses has been used to study the femtosecond laser-induced solid-to-liquid phase transition in a thin crystalline layer of germanium. Nonthermal melting is observed to take place within 300-500 fs. Following ultrafast melting we observe strong acoustic perturbations evolving on a picosecond time scale. Y1 - 2001 U6 - https://doi.org/10.1103/PhysRevLett.87.225701 VL - 87 PB - APS ER -