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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  - 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  -