@article{ZhuangSchellingStangletal.2000, author = {Zhuang, Y. and Schelling, Christoph and Stangl, Jochen and Penn, C. and Senz, S. and Sch{\"a}ffler, Friedrich and Roche, T. and Daniel, A. and Grenzer, J{\"o}rg and Pietsch, Ullrich and Bauer, G{\"u}nther}, title = {Structural and optical properties of Si/Si{1-x}Ge{x} wires}, year = {2000}, language = {en} } @article{ZhuangPietschStangletal.2000, author = {Zhuang, Y. and Pietsch, Ullrich and Stangl, Jochen and Hol{\´y}, Vaclav and Darowski, Nora and Grenzer, J{\"o}rg and Zerlauth, S. and Sch{\"a}ffler, F. and Bauer, G{\"u}nther}, title = {In-plane strain and shape analysis of Si/SiGe nanostructures by grazing incidence diffraction}, year = {2000}, language = {en} } @article{ZhuangHolyStangletal.1999, author = {Zhuang, Y. and Hol{\´y}, V{\´a}clav and Stangl, Jochen and Darhuber, A. and Mikulik, P. and Zerlauth, S. and Sch{\"a}ffler, F. and Bauer, G{\"u}nther and Darowski, Nora and L{\"u}bbert, Daniel and Pietsch, Ullrich}, title = {Strain relaxation in periodic arrays of Si/SiGe quantum wires determined by coplanar high-resolution x-ray diffrcation and grazing-incidence diffraction}, year = {1999}, language = {en} } @article{ZenSaphiannikovaNeheretal.2006, author = {Zen, Achmad and Saphiannikova, Marina and Neher, Dieter and Grenzer, J{\"o}rg and Grigorian, Souren A. and Pietsch, Ullrich and Asawapirom, Udom and Janietz, Silvia and Scherf, Ullrich and Lieberwirth, Ingo and Wegner, Gerhard}, title = {Effect of molecular weight on the structure and crystallinity of poly(3-hexylthiophene)}, doi = {10.1021/Ma0521349}, year = {2006}, abstract = {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}, language = {en} } @article{ZeimerPietschGrenzeretal.2005, author = {Zeimer, Ute and Pietsch, Ullrich and Grenzer, Joerg and Fricke, J. and Knauer, A. and Weyers, Markus}, title = {Optimised two layer overgrowth of a lateral strain-modulated nanostructure}, issn = {0925-8388}, year = {2005}, abstract = {Recently it has been shown that lateral carrier confinement in an InGaAs quantum well (QW) embedded in GaAs can be achieved by using a laterally patterned InGaP stressor layer on top of the heterostructure. To exploit this effect in a device the structure has to be planarized by a second epitaxial step. It has been shown that the lateral strain modulation almost vanishes after overgrowth with GaAs, whereas overgrowth with a single ternary layer of opposite strain compared to the stressor layer suffers from strain induced decomposition. Here we show that the lateral carrier confinement of the initially free standing nanostructure can almost be maintained using a two step process for overgrowth, where a strained thin ternary layer is grown first followed by GaAs up to complete planarization of the patterned structure. Thickness and composition of the ternary layer are adjusted on the basis of finite element calculations of the strain distribution (FEM). The strain field achieved after overgrowth is probed by X-ray grazing- incidence diffraction (GID). (c) 2005 Elsevier B.V. All rights reserved}, language = {en} } @article{ZeimerGrenzerPietschetal.2001, author = {Zeimer, Ute and Grenzer, J{\"o}rg and Pietsch, Ullrich and Bugge, F. and Smirnitzki, V. and Weyers, Markus}, title = {Investigation of strain-modulated InGaAs-nanostructures by grazing-incidence x-ray diffraction and photoluminescence}, year = {2001}, language = {en} } @article{ZeimerBuggeGramlichetal.2001, author = {Zeimer, Ute and Bugge, F. and Gramlich, S. and Smirnitzki, V. and Weyers, Markus and Tr{\"a}nkle, G. and Grenzer, J{\"o}rg and Pietsch, Ullrich and Cassabois, G. and Emiliani, V. and Linau, Christoph}, title = {Evidence of strain-induced lateral carrier confinement in InGaAs-quantum wells by low-temperature near-field spectroscopy}, year = {2001}, language = {en} } @article{ZeimerBuggeGramlichetal.2000, author = {Zeimer, Ute and Bugge, F. and Gramlich, S. and Smirnitzki, V. and Weyers, Markus and Tr{\"a}nkle, G. and Grenzer, J{\"o}rg and Pietsch, Ullrich and Cassabois, G. and Emiliani, V. and Lienau, C.}, title = {Evidence for strain-induced lateral carrier confinement in InGaAs quantum wells by low-temperature near-field spectroscopy}, year = {2000}, language = {en} } @article{ZeimerBaumbachGrenzeretal.1999, author = {Zeimer, Ute and Baumbach, Tilo and Grenzer, J{\"o}rg and L{\"u}bbert, Daniel and Mazuelas, A. and Pietsch, Ullrich and Erbert, G.}, title = {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}, year = {1999}, language = {en} } @article{VeldkampErkoGudatetal.1999, author = {Veldkamp, Markus and Erko, Alexei and Gudat, Wolfgang and Abrosimov, Nikolai V. and Alex, Volker and Khasanov, Salavat and Neissendorfer, Frank and Pietsch, Ullrich and Shekhtman, Veniamin}, title = {Si(1-x)Ge(x) laterally graded crystals as monochromators for X-Ray absorption spectroscopy studies}, year = {1999}, language = {en} }