TY  - JOUR
A1  - Zhuang, Y.
A1  - Schelling, Christoph
A1  - Stangl, Jochen
A1  - Penn, C.
A1  - Senz, S.
A1  - Schäffler, Friedrich
A1  - Roche, T.
A1  - Daniel, A.
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Bauer, Günther
T1  - Structural and optical properties of Si/Si{1-x}Ge{x} wires
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zhuang, Y.
A1  - Pietsch, Ullrich
A1  - Stangl, Jochen
A1  - Holý, Vaclav
A1  - Darowski, Nora
A1  - Grenzer, Jörg
A1  - Zerlauth, S.
A1  - Schäffler, F.
A1  - Bauer, Günther
T1  - In-plane strain and shape analysis of Si/SiGe nanostructures by grazing incidence diffraction
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zen, Achmad
A1  - Saphiannikova, Marina
A1  - Neher, Dieter
A1  - Grenzer, Jörg
A1  - Grigorian, Souren A.
A1  - Pietsch, Ullrich
A1  - Asawapirom, Udom
A1  - Janietz, Silvia
A1  - Scherf, Ullrich
A1  - Lieberwirth, Ingo
A1  - Wegner, Gerhard
T1  - Effect of molecular weight on the structure and crystallinity of poly(3-hexylthiophene)
N2  - Recently, two different groups have reported independently that the mobility of field-effect transistors made from regioregular poly(3-hexylthiophene) (P3HT) increases strongly with molecular weight. Two different models were presented: one proposing carrier trapping at grain boundaries and the second putting emphasis on the conformation and packing of the polymer chains in the thin layers for different molecular weights. Here, we present the results of detailed investigations of powders and thin films of deuterated P3HT fractions with different molecular weight. For powder samples, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) were used to investigate the structure and crystallization behavior of the polymers. The GPC investigations show that all weight fractions possess a rather broad molecular weight distribution. DSC measurements reveal a strong decrease of the crystallization temperature and, most important, a significant decrease of the degree of crystallinity with decreasing molecular weight. To study the structure of thin layers in lateral and vertical directions, both transmission electron microscopy (TEM) and X-ray grazing incidence diffraction (GID) were utilized. These methods show that thin layers of the low molecular weight fraction consist of well-defined crystalline domains embedded in a disordered matrix. We propose that the transport properties of layers prepared from fractions of poly(3-hexylthiophene) with different molecular weight are largely determined by the crystallinity of the samples and not by the perfection of the packing of the chains in the individual crystallites
Y1  - 2006
UR  - http://pubs.acs.org/doi/full/10.1021/ma0521349
U6  - https://doi.org/10.1021/Ma0521349
ER  - 
TY  - JOUR
A1  - Zen, Achmad
A1  - Bilge, Askin
A1  - Galbrecht, Frank
A1  - Alle, Ronald
A1  - Meerholz, Klaus
A1  - Grenzer, Jörg
A1  - Neher, Dieter
A1  - Scherf, Ullrich
A1  - Farrell, Tony
T1  - Solution processable organic field-effect transistors utilizing an alpha,alpha '-dihexylpentathiophene- based swivel cruciform
Y1  - 2006
UR  - http://pubs.acs.org/doi/full/10.1021/ja0573357
U6  - https://doi.org/10.1021/Ja0573357
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Bugge, F.
A1  - Smirnitzki, V.
A1  - Weyers, Markus
T1  - Investigation of strain-modulated InGaAs-nanostructures by grazing-incidence x-ray diffraction and photoluminescence
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Bugge, F.
A1  - Gramlich, S.
A1  - Smirnitzki, V.
A1  - Weyers, Markus
A1  - Tränkle, G.
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Cassabois, G.
A1  - Emiliani, V.
A1  - Linau, Christoph
T1  - Evidence of strain-induced lateral carrier confinement in InGaAs-quantum wells by low-temperature near-field spectroscopy
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Bugge, F.
A1  - Gramlich, S.
A1  - Smirnitzki, V.
A1  - Weyers, Markus
A1  - Tränkle, G.
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Cassabois, G.
A1  - Emiliani, V.
A1  - Lienau, C.
T1  - Evidence for strain-induced lateral carrier confinement in InGaAs quantum wells by low-temperature near-field spectroscopy
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Zeimer, Ute
A1  - Baumbach, Tilo
A1  - Grenzer, Jörg
A1  - Lübbert, Daniel
A1  - Mazuelas, A.
A1  - Pietsch, Ullrich
A1  - Erbert, G.
T1  - In-situ characterization of strain distribution in broad-area high-power lasers under operation by high- resolution x-ray diffrcation and topography using synchrotron radiation
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Ulyanenkov, A.
A1  - Darowski, Nora
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Wang, K. H.
A1  - Forchel, Alfred
T1  - Evaluation of strain distribution in freestanding and bruied lateral nanostructures
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Talalaev, V
A1  - Tomm, JW
A1  - Elsaesser, T
A1  - Zeimer, Ute
A1  - Fricke, J
A1  - Knauer, A
A1  - Kissel, H
A1  - Weyers, Markus
A1  - Tarasov, GG
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
T1  - Carrier dynamics in laterally strain-modulated InGaAs quantum wells
N2  - We investigate the transient recombination and transfer properties of nonequilibrium carriers in an In0.16Ga0.84As/GaAs quantum well (QW) with an additional lateral confinement implemented by a patterned stressor layer. The structure thus contains QW- and quantum-wire-like areas. At low excitation densities, photoluminescence (PL) transients from both areas are well described by a rate equation model for a three-level system with a saturable interlevel carrier transfer representing the lateral drift of carriers from the QW regions into the wires. Small-signal carrier lifetimes for QW, wires, and transfer time from QW to wire are 180, 190, and 28 ps, respectively. For high excitation densities the time constants of the observed transients increase, in agreement with the model. In addition, QW and wire PL lines merge indicating a smoothening of the potential difference, i.e., the effective carrier confinement caused by the stressor structure becomes weaker with increasing excitation. (c) 2005 American Institute of Physics
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Stahn, Jochen
A1  - Geue, Thomas
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
T1  - Interaction of short-chain alkanes with surface and interfaces of multilayer films built from amphiphilic molecules: an in-situ X-ray and neutron scattering probe
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Zeimer, Ute
A1  - Hofmann, L.
A1  - Grenzer, Jörg
A1  - Gramlich, S.
T1  - Strain induced compositional modulations in AlGaAs overlayers induced by lateral surface gratings
Y1  - 2001
SN  - 0272-9172
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Zeimer, Ute
A1  - Grenzer, Jörg
A1  - Grigorian, Souren A.
A1  - Fricke, J.
A1  - Gramlich, S.
A1  - Bugge, F.
A1  - Weyers, Markus
A1  - Trankle, G.
T1  - Influence of lateral patterning geometry on lateral carrier confinement in strain-modulated InGaAs- nanostructures
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Panzner, Tobias
A1  - Leitenberger, Wolfram
A1  - Grenzer, Jörg
A1  - Bodenthin, Th.
A1  - Geue, Thomas
A1  - Möhwald, Helmuth
T1  - Coherence experiments at the energy-dispersive reflectometry beamline at BESSY II
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Mukhopadhyay, M. K.
A1  - Sanyal, M. K.
A1  - Datta, A.
A1  - Mukherjee, M.
A1  - Geue, Thomas
A1  - Grenzer, Jörg
T1  - Transition from two-dimensional to three-dimensional melting in Langmuir-Blodgett films
N2  - Results of energy-dispersive x-ray reflectivity and grazing incidence diffraction studies of Langmuir-Blodgett films exhibited evolution of conventional three-dimensional melting from continuous melting, characteristic of two- dimensional systems, as a function of deposited monolayers. Continuous expansion followed by a sharp phase transition of the in-plane lattice was observed before the melting point and found to be independent of number of deposited layers. Evolution of conventional melting with an increase in the number of monolayers could be quantified by measuring stiffness against tilting of the vertical stack of molecules, which are kept together by an internal field. The internal field as defined in this model reduces as the in-plane lattice expands and the sample temperature approaches melting point. The sharpness of the melting transition, which has been approximated by a Langevin function, increases with the number of deposited monolayers
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Leitenberger, Wolfram
A1  - Wendrock, Horst
A1  - Bischoff, Lothar
A1  - Panzner, Tobias
A1  - Grenzer, Jörg
A1  - Pucher, Andreas
T1  - Double pinhole diffraction of white synchrotron radiation
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Hazra, S.
A1  - Chini, T. K.
A1  - Sanyal, M. K.
A1  - Grenzer, Jörg
T1  - Ripple structure of crystalline layers in ion beam induced Si wafers
N2  - Ion-beam-induced ripple formation in Si wafers was studied by two complementary surface sensitive techniques, namely atomic force microscopy (AFM) and depth-resolved x-ray grazing incidence diffraction (GID). The formation of ripple structure at high doses (similar to7x10(17) ions/cm(2)), starting from initiation at low doses (similar to1x10(17) ions/cm(2)) of ion beam, is evident from AFM, while that in the buried crystalline region below a partially crystalline top layer is evident from GID study. Such ripple structure of crystalline layers in a large area formed in the subsurface region of Si wafers is probed through a nondestructive technique. The GID technique reveals that these periodically modulated wavelike buried crystalline features become highly regular and strongly correlated as one increases the Ar ion-beam energy from 60 to 100 keV. The vertical density profile obtained from the analysis of a Vineyard profile shows that the density in the upper top part of ripples is decreased to about 15% of the crystalline density. The partially crystalline top layer at low dose transforms to a completely amorphous layer for high doses, and the top morphology was found to be conformal with the underlying crystalline ripple
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Grigorian, Souren A.
A1  - Grenzer, Jörg
A1  - Vartanyants, Ivan A.
T1  - Thermal diffuse scattering in grazing incidence diffraction
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Grigorian, Souren A.
A1  - Grenzer, Jörg
A1  - Feranchuk, S.
A1  - Zeimer, Ute
T1  - Grazing-incidence diffraction study of strain-modulated single quantum well nanostructures
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Grenzer, Jörg
A1  - Grigorian, Souren A.
A1  - Weyers, Markus
A1  - Zeimer, Ute
A1  - Feranchuk, S.
A1  - Fricke, J.
A1  - Kissel, H.
A1  - Knauer, A.
A1  - Tränkle, G.
T1  - Nanoengineering of lateral strain-modulation in quantum well heterostructures
N2  - We have developed a method to design a lateral band-gap modulation in a quantum well heterostructure. The lateral strain variation is induced by patterning of a stressor layer grown on top of a single quantum well which itself is not patterned. The three-dimensional (3D) strain distribution within the lateral nanostructure is calculated using linear elasticity theory applying a finite element technique. Based on the deformation potential approach the calculated strain distribution is translated into a local variation of the band-gap energy. Using a given vertical layer structure we are able to optimize the geometrical parameters to provide a nanostructure with maximum lateral band-gap variation. Experimentally such a structure was realized by etching a surface grating into a tensile-strained InGaP stressor layer grown on top of a compressively strained InGaAs-single quantum well. The achieved 3D strain distribution and the induced band-gap variation are successfully probed by x-ray grazing incidence diffraction and low-temperature photoluminescence measurements, respectively
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Grenzer, Jörg
A1  - Geue, Thomas
A1  - Neißendorfer, Frank
A1  - Brezesinski, Gerald
A1  - Symietz, Christian
A1  - Möhwald, Helmuth
A1  - Gudat, Wolfgang
T1  - The energy dispersive reflectometer at BESSY II : a challenge for thin film analysis
Y1  - 2001
SN  - 0167- 5087
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Grenzer, Jörg
A1  - Bischoff, Lothar
T1  - Grazing-incidence diffraction strain analysis of a laterally patterned Si wafer treated by focused Ge and An ion beam implantation
N2  - Strain analysis of a laterally patterned Si-wafer was carried out utilizing X-ray grazing-incidence diffraction with synchrotron radiation. The lateral patterning was done by focused ion beam implantation using an ion source of liquid AuGeSi alloy. Samples were prepared by either 35 keV Au+ ions (dose: 0.2, 2 x 10(14) cm(-2)) or 70 keV Ge++ ions (dose: 8 X 10(14) cm(-1)). It was shown that due to implantation a periodical defect structure is created consisting of both implanted and not implanted stripes. The evaluated depth distribution of defects within the implanted stripes corresponds to that obtained by TRIM calculation. The induced strain distribution, however, shows no periodicity. This can be explained by an overlap of the strain fields created in each implanted stripe. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Darowski, Nora
A1  - Ulyanenkov, A.
A1  - Grenzer, Jörg
A1  - Wang, K. H.
A1  - Forchel, Alfred
T1  - Analysis of the strain distribution in lateral nanostructures for interpreting photoluminescence data
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Bodenthin, Yves
A1  - Grenzer, Jörg
A1  - Geue, Thomas
A1  - Möhwald, Helmuth
A1  - Kurth, Dirk G.
T1  - Structure and temperature behavior of metallo-supramolecular assemblies
N2  - A detailed structural analysis of a Langmuir-Blodgett (LB) multilayer composed of a polyelectrolyte-amphiphile complex (PAC) is presented. The PAC is self-assembled from metal ions, ditopic bis-terpyridines, and amphiphiles. The vertical structure of the LB multilayer is investigated by X-ray reflectometry. The multilayer has a periodicity of 57 A, which corresponds to an architecture of flat lying metallo-supramolecular coordination polyelectrolyte (MEPE) rods and upright-standing amphiphiles (dihexadecyl phosphate, DHP). In-plane diffraction reveals hexagonal packing of the DHP molecules. Using extended X-ray absorption fine structure (EXAFS) experiments, we prove that the central metal ion is coordinated to the terpyridine moieties in a pseudo-octahedral coordination environment. The Fe-N bond distances are 1.82 and 2.0 angstrom, respectively. Temperature resolved measurements indicate a reversible phase transition in a temperature range up to 55 degrees C. EXAFS measurements indicate a lengthening of the average Fe-N bond distance from 1.91 to 1.95 angstrom. The widening of the coordination cage upon heating is expected to lower the ligand field stabilization, thus giving rise to spin transitions in these composite materials
Y1  - 2005
ER  - 
TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Bhattacharya, M. K.
A1  - Mukherjee, M.
A1  - Sanyal, M. K.
A1  - Geue, Thomas
A1  - Grenzer, Jörg
T1  - Energy dispersive x-ray reflectivity technique to study thermal properties of polymer films
Y1  - 2003
ER  - 
TY  - JOUR
A1  - Mukherjee, M.
A1  - Bhattacharya, M. K.
A1  - Sanyal, M. K.
A1  - Geue, Thomas
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
T1  - Temperature dependent thickness and surface tension of polymer films
Y1  - 2000
SN  - 81-7371295-6
ER  - 
TY  - JOUR
A1  - Karcenko, Anatolij V.
A1  - Englisch, Uwe
A1  - Grenzer, Jörg
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Siebrecht, R.
T1  - Investigation of partially deuterated multilayers by means of X-ray and polarized neutron reflectometry
Y1  - 2000
SN  - 1044-8632
ER  - 
TY  - GEN
A1  - Hesse, Julia
A1  - Klier, Dennis Tobias
A1  - Sgarzi, Massimo
A1  - Nsubuga, Anne
A1  - Bauer, Christoph
A1  - Grenzer, Jörg
A1  - Hübner, René
A1  - Wislicenus, Marcus
A1  - Joshi, Tanmaya
A1  - Kumke, Michael Uwe
A1  - Stephan, Holger
T1  - Rapid synthesis of sub-10 nm hexagonal NaYF4-based upconverting nanoparticles using Therminol® 66
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We report a simple one-pot method for the rapid preparation of sub-10nm pure hexagonal (-phase) NaYF4-based upconverting nanoparticles (UCNPs). Using Therminol((R))66 as a co-solvent, monodisperse UCNPs could be obtained in unusually short reaction times. By varying the reaction time and reaction temperature, it was possible to control precisely the particle size and crystalline phase of the UCNPs. The upconversion (UC) luminescence properties of the nanocrystals were tuned by varying the concentrations of the dopants (Nd3+ and Yb3+ sensitizer ions and Er3+ activator ions). The size and phase-purity of the as-synthesized core and core-shell nanocrystals were assessed by using complementary transmission electron microscopy, dynamic light scattering, X-ray diffraction, and small-angle X-ray scattering studies. In-depth photophysical evaluation of the UCNPs was pursued by using steady-state and time-resolved luminescence spectroscopy. An enhancement in the UC intensity was observed if the nanocrystals, doped with optimized concentrations of lanthanide sensitizer/activator ions, were further coated with an inert/active shell. This was attributed to the suppression of surface-related luminescence quenching effects.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 613 
KW  - core-shell materials
KW  - lanthanides
KW  - nanostructures
KW  - photoluminescence
KW  - upconversion
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-423515
SN  - 1866-8372
IS  - 613
ER  - 
TY  - JOUR
A1  - Grenzer, Jörg
A1  - Schomburg, E.
A1  - Lingott, I.
A1  - Ignotov, A. a.
A1  - Renk, K. F.
A1  - Pietsch, Ullrich
A1  - Rose, Dirk
A1  - Zeimer, Ute
A1  - Melzer, B. J.
A1  - Ivanov, S.
A1  - Schaposchnikov, S.
A1  - Kop'ev, P. S.
A1  - Pavel'ev, D. G.
A1  - Koschurinov, Yu.
T1  - X-ray and transport characterization of an Esaki-Tsu superlattice device
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Grenzer, Jörg
A1  - Darowski, Nora
A1  - Pietsch, Ullrich
A1  - Daniel, A.
A1  - Reithmaier, Johann-Peter
A1  - Rennon, Siegfried
A1  - Forchel, Alfred
T1  - Grazing-incidence diffraction strain analysis of a laterally-modulated multiquantum well system produced by focused-ion-beam implantation
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Grenzer, Jörg
A1  - Darowski, Nora
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Daniel, A.
A1  - Rennon, Siegfried
A1  - Reithmaier, Johann-Peter
A1  - Forchel, Alfred
T1  - Strain analysis and quantum well intermixing of a laterally modulated multiquantum well system produced by focused ion beam implantation
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Geue, Thomas
A1  - Schultz, Michael
A1  - Grenzer, Jörg
A1  - Natansohn, Almeria
A1  - Rochon, Paul
T1  - X-ray investigations of the molecular mobility with polymer surface gratings
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Geue, Thomas
A1  - Henneberg, Oliver
A1  - Grenzer, Jörg
A1  - Pietsch, Ullrich
A1  - Natansohn, Almeria
A1  - Rochon, Paul
A1  - Finkelstein, Kenneth D.
T1  - Formation of a buried density grating on thermal erasure of azobenzene polymer surface gratings
Y1  - 2002
SN  - 0927-7757
ER  - 
TY  - JOUR
A1  - Bodenthin, Yves
A1  - Grenzer, Jörg
A1  - Lauter, Robert
A1  - Pietsch, Ullrich
A1  - Lehmann, Pit
A1  - Kurth, Dirk G.
A1  - Möhwald, Helmuth
T1  - Temperature and time resolved x-ray scattering at thin organic films
Y1  - 2002
ER  -