@article{4548, abstract = {{A fluorescence study of acetonitrile solutions of bis(tetramethylguanidine)propane, copper(I)-iodide and [Cu(btmgp)I] was performed and the chemical reaction of the latter species with O2 was investigated at room temperature. The actual quenching process via O2 gassing was studied and an exponential dependence of the fluorescence intensity with respect to the complex concentration was observed. Furthermore the survey was deepened on time resolved fluorescence properties of solved [Cu(btmgp)I] in a wider concentration range. The applicability of this complex for O2 sensing inside a microreactor system was proven by confocal fluorescence measurements. It was shown that the investigated system can be used for oxygen sensing in the copper concentration range from 10−2 to 10−9 mol/l.}}, author = {{Herres-Pawlis, Sonja and Berth, Gerhard and Wiedemeier, Volker and Schmidt, Ludger and Zrenner, Artur and Warnecke, Hans-Joachim}}, issn = {{0022-2313}}, journal = {{Journal of Luminescence}}, keywords = {{Copper Oxygen Fluorescence quenching N donor ligands}}, number = {{10}}, pages = {{1958--1962}}, publisher = {{Elsevier BV}}, title = {{{Oxygen sensing by fluorescence quenching of [Cu(btmgp)I]}}}, doi = {{10.1016/j.jlumin.2010.05.012}}, volume = {{130}}, year = {{2010}}, } @article{4549, abstract = {{Damage caused by laser irradiation on the surface of ZnTe epilayers was studied by micro-Raman and atomic force microscopy (AFM). ZnTe LO-phonon overtones up to four order and TO + (n − 1)LO zone-center phonons were observed in the resonant micro-Raman spectra at room temperature. Discrepancies in the literature regarding the origin of two features observed at low frequencies around 120 and 140 cm−1 in the Raman spectrum of ZnTe are discussed and resolved. These Raman peaks were not detected by using a low excitation laser power density on a Zn-terminated ZnTe surface; however, with the increase of the laser power density they were found to arise irreversibly. The correspondence of these peaks in a wave number with the strongest Raman peaks of the crystalline tellurium phase and the intensity enhancement behavior with the laser power in a similar way as for CdTe strongly suggests the formation of crystalline tellurium aggregates on the layer surface due to laser irradiation damage. AFM data reveal the occurrence of laser ablation on the ZnTe surface even though the surface temperature of the sample is below the melting point.}}, author = {{Larramendi, E M and Berth, Gerhard and Wiedemeier, V and Hüsch, K-P and Zrenner, Artur and Woggon, U and Tschumak, E and Lischka, K and Schikora, D}}, issn = {{0268-1242}}, journal = {{Semiconductor Science and Technology}}, number = {{7}}, publisher = {{IOP Publishing}}, title = {{{Intensity enhancement of Te Raman modes by laser damage in ZnTe epilayers}}}, doi = {{10.1088/0268-1242/25/7/075003}}, volume = {{25}}, year = {{2010}}, } @article{4550, abstract = {{We have integrated individual (In,Ga)As quantum dots (QDs) using site-controlled molecular beam epitaxial growth into the intrinsic region of a p-i-n junction diode. This is achieved using an in situ combination of focused ion beam prepatterning, annealing, and overgrowth, resulting in arrays of individually electrically addressable (In,Ga)As QDs with full control on the lateral position. Using microelectroluminescence spectroscopy we demonstrate that these QDs have the same optical quality as optically pumped Stranski–Krastanov QDs with random nucleation located in proximity to a doped interface. The results suggest that this technique is scalable and highly interesting for different applications in quantum devices.}}, author = {{Mehta, M. and Reuter, Dirk and Wieck, A. D. and Michaelis de Vasconcellos, S. and Zrenner, Artur and Meier, Cedrik}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{14}}, publisher = {{AIP Publishing}}, title = {{{An intentionally positioned (In,Ga)As quantum dot in a micron sized light emitting diode}}}, doi = {{10.1063/1.3488812}}, volume = {{97}}, year = {{2010}}, } @article{4551, abstract = {{An intentional positioning of optically active quantum dots using site-selective growth by a combination of molecular beam epitaxy (MBE) and focused ion beam (FIB) implantation in an all-ultra-high-vacuum (UHV) setup has been successfully demonstrated. A square array of periodic holes on GaAs substrate was fabricated with FIB of 30 keV ions followed by an in situ annealing step. Subsequently, the patterned holes were overgrown with an optimized amount of InAs in order to achieve site-selective growth of the QDs on the patterned holes. Under well-optimized conditions, a selectivity of single quantum dot growth in the patterned holes of 52% was achieved. Thereafter, carrier injection and subsequent radiative recombination from the positioned InAs/GaAs self-assembled QDs was investigated by embedding the QDs in the intrinsic part of a GaAs-based p–i–n junction device. Electroluminescence spectra taken at 77 K show interband transitions up to the fifth excited state from the QDs.}}, author = {{Mehta, Minisha and Reuter, Dirk and Melnikov, Alexander and Wieck, Andreas D. and Michaelis de Vasconcellos, Steffen and Baumgarten, Tim and Zrenner, Artur and Meier, Cedrik}}, issn = {{1386-9477}}, journal = {{Physica E: Low-dimensional Systems and Nanostructures}}, keywords = {{Molecular beam epitaxy, Focused ion beam, Self-assembled quantum dot, Electroluminescence}}, number = {{10}}, pages = {{2749--2752}}, publisher = {{Elsevier BV}}, title = {{{Intentionally positioned self-assembled InAs quantum dots in an electroluminescent p–i–n junction diode}}}, doi = {{10.1016/j.physe.2009.12.053}}, volume = {{42}}, year = {{2010}}, } @article{4552, abstract = {{Here we report on investigations on CdSe quantum dots incorporated in ZnSe based Schottky photodiodes with near-field shadow masks. Photoluminescence and photocurrent of individual quantum dots were studied as a function of the applied bias voltage. The exciton energy of the quantum dot ground state transition was shifted to the excitation energy by using the Stark effect tuning via an external bias voltage. Under the condition of resonance with the laser excitation energy we observed a resonant photocurrent signal due to the tunnelling of carriers out of the quantum dots at electric fields above 500 kV/cm.}}, author = {{Panfilova, M. and Michaelis de Vasconcellos, S. and Pawlis, A. and Lischka, K. and Zrenner, Artur}}, issn = {{1386-9477}}, journal = {{Physica E: Low-dimensional Systems and Nanostructures}}, keywords = {{CdSe/ZnSe quantum dots, Photodiode, Quantum confined Stark Effect, Photocurrent, II–VI Semiconductors}}, number = {{10}}, pages = {{2521--2523}}, publisher = {{Elsevier BV}}, title = {{{Resonant photocurrent-spectroscopy of individual CdSe quantum dots}}}, doi = {{10.1016/j.physe.2010.01.013}}, volume = {{42}}, year = {{2010}}, } @inproceedings{7251, author = {{Ishikawa, Atsushi and Oulton, Rupert F. and Zentgraf, Thomas and Zhang, Xiang}}, booktitle = {{Plasmonics: Metallic Nanostructures and Their Optical Properties VIII}}, editor = {{Stockman, Mark I.}}, publisher = {{SPIE}}, title = {{{Extremely low-loss slow-light modes in plasmonic dielectric hybrid systems}}}, doi = {{10.1117/12.860190}}, year = {{2010}}, } @inproceedings{7252, author = {{Sorger, Volker J. and Oulton, Rupert F. and Zentgraf, Thomas and Ma, Renmin and Gladden, Christopher and Dai, Lun and Bartal, Guy and Zhang, Xiang}}, booktitle = {{Plasmonics: Metallic Nanostructures and Their Optical Properties VIII}}, editor = {{Stockman, Mark I.}}, publisher = {{SPIE}}, title = {{{Semiconductor plasmon laser}}}, doi = {{10.1117/12.859136}}, year = {{2010}}, } @article{7494, author = {{Mehta, M. and Meier, Cedrik}}, issn = {{0013-4651}}, journal = {{Journal of The Electrochemical Society}}, number = {{2}}, publisher = {{The Electrochemical Society}}, title = {{{Controlled Etching Behavior of O-Polar and Zn-Polar ZnO Single Crystals}}}, doi = {{10.1149/1.3519999}}, volume = {{158}}, year = {{2010}}, } @article{7496, author = {{Theis, Jens and Geller, Martin and Lorke, Axel and Wiggers, Hartmut and Wieck, Andreas and Meier, Cedrik}}, issn = {{0957-4484}}, journal = {{Nanotechnology}}, number = {{45}}, publisher = {{IOP Publishing}}, title = {{{Electroluminescence from silicon nanoparticles fabricated from the gas phase}}}, doi = {{10.1088/0957-4484/21/45/455201}}, volume = {{21}}, year = {{2010}}, } @article{4129, abstract = {{We study a single quantum dot molecule doped with one electron in the presence of electron-phonon coupling. Both diagonal and off-diagonal interactions representing real and virtual processes with acoustic phonons via deformation potential and piezoelectric coupling are taken into account. We employ a non-perturbative quantum kinetic theory and show that the phonon-mediated relaxation is dominated by an electron tunneling on a picosecond time scale.A dependence of the relaxation on the temperature and the strength of the tunneling coupling is analyzed.}}, author = {{Grodecka-Grad, Anna and Förstner, Jens}}, issn = {{1742-6596}}, journal = {{Journal of Physics: Conference Series}}, keywords = {{tet_topic_qd}}, publisher = {{IOP Publishing}}, title = {{{Phonon-mediated relaxation in doped quantum dot molecules}}}, doi = {{10.1088/1742-6596/245/1/012035}}, volume = {{245}}, year = {{2010}}, } @article{4144, abstract = {{Non-polar relaxed cubic GaN was grown by molecular beam epitaxy (MBE) on nano-patterned 3C-SiC/Si (0 0 1)substrates with negligible hexagonal content and less defect density than in planar cubic GaN layers.Nano-patterning of 3C-SiC/Si(001) is achieved by self-ordered colloidal masks for the first time. The method presented here offers the possibility to create nano-patterned cubic GaN without the need for a GaN etching process andt hus isa potential alternative to the conventional top–down fabrication techniques.}}, author = {{Kemper, R.M. and Weinl, M. and Mietze, C. and Häberlen, M. and Schupp, T. and Tschumak, E. and Lindner, Jörg and Lischka, K. and As, Donald }}, issn = {{0022-0248}}, journal = {{Journal of Crystal Growth}}, number = {{1}}, pages = {{84--87}}, publisher = {{Elsevier BV}}, title = {{{Growth of cubic GaN on nano-patterned 3C-SiC/Si (001) substrates}}}, doi = {{10.1016/j.jcrysgro.2010.12.042}}, volume = {{323}}, year = {{2010}}, } @article{4153, abstract = {{Nanosphere lithography (NSL) masks consisting of mono- or double-layers of polystyrene (PS) nano-beads are fabricated on silicon exploiting the self-organization of PS particles during the controlled drying of a colloidal suspension on a surface. The shape changes and shrinkage of PS sphere masks upon treatment in an air plasma are studied as a function of initial sphere size, plasma power and treatment time. The influence of several experimental parameters, including the plasma induced temperature rise, are analysed using scanning and transmission electron microscopy. It is demonstrated that a variety of new intriguing nanopatterns can be generated on silicon surfaces by the combination of NSL and plasma techniques, largely broadening the variety of patterns available so far by NSL.}}, author = {{Gogel, D. and Weinl, M. and Lindner, Jörg and Stritzker, B.}}, journal = {{JOURNAL OF OPTOELECTRONICS AND ADVANCED MATERIALS}}, number = {{3}}, pages = {{740--744}}, title = {{{Plasma modification of nanosphere lithography masks made of polystyrene beads}}}, volume = {{12}}, year = {{2010}}, } @article{4174, abstract = {{A quantum dot molecule doped with a single electron in the presence of diagonal and off-diagonal carrierphonon couplings is studied by means of a nonperturbative quantum kinetic theory. The interaction with acoustic phonons by deformation potential and piezoelectric coupling is taken into account. We show that the phonon-mediated relaxation is fast on a picosecond time scale and is dominated by the usually neglected off-diagonal coupling to the lattice degrees of freedom leading to phonon-assisted electron tunneling. We show that in the parameter regime of current electrical and optical experiments, the microscopic non-Markovian theory has to be employed.}}, author = {{Grodecka-Grad, A. and Förstner, Jens}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, keywords = {{tet_topic_qd}}, number = {{11}}, publisher = {{American Physical Society (APS)}}, title = {{{Theory of phonon-mediated relaxation in doped quantum dot molecules}}}, doi = {{10.1103/physrevb.81.115305}}, volume = {{81}}, year = {{2010}}, } @article{4194, abstract = {{A heterojunction field-effect transistor (HFET) was fabricated of nonpolar cubic AlGaN/GaN grown on Ar+ implanted 3C–SiC (001) by molecular beam epitaxy. The device shows a clear field effect at positive bias voltages with V_th=0.6 V. The HFET output characteristics were calculated using ATLAS simulation program. The electron channel at the cubic AlGaN/GaN interface was detected by room temperature capacitance-voltage measurements.}}, author = {{Tschumak, E. and Granzner, R. and Lindner, Jörg and Schwierz, F. and Lischka, K. and Nagasawa, H. and Abe, M. and As, Donald}}, issn = {{0003-6951}}, journal = {{Applied Physics Letters}}, number = {{25}}, publisher = {{AIP Publishing}}, title = {{{Nonpolar cubic AlGaN/GaN heterojunction field-effect transistor on Ar+ implanted 3C–SiC (001)}}}, doi = {{10.1063/1.3455066}}, volume = {{96}}, year = {{2010}}, } @article{4200, abstract = {{We studied the Fulde-Ferrell-Larkin-Ovchinnikov-type state established due to the proximity effect in superconducting Nb/Cu_41Ni_59 bilayers. Using a special wedge-type deposition technique, series of 20–35 samples could be fabricated by magnetron sputtering during one run. The layer thickness of only a few nanometers, the composition of the alloy, and the quality of interfaces were controlled by Rutherford backscattering spectrometry, high-resolution transmission electron microscopy, and Auger spectroscopy. The magnetic properties of the ferromagnetic alloy layer were characterized with superconducting quantum interference device magnetometry. These studies yield precise information about the thickness and demonstrate the homogeneity of the alloy composition and magnetic properties along the sample series. The dependencies of the critical temperature on the Nb and Cu41Ni59 layer thickness, T_c(d_S) and T_c(d_F), were investigated for constant thickness d_F of the magnetic alloy layer and d_S of the superconducting layer, respectively. All types of nonmonotonic behaviors of T_c versus d_F predicted by the theory could be realized experimentally, from reentrant superconducting behavior with a broad extinction region to a slight suppression of superconductivity with a shallow minimum. Even a double extinction of superconductivity was observed, giving evidence for the multiple reentrant behavior predicted by theory. All critical temperature curves were fitted with suitable sets of parameters. Then, T_c(d_F) diagrams of a hypothetical ferromagnet/superconductor/ferromagnet spin-switch core structure were calculated using these parameters. Finally, superconducting spin-switch fabrication issues are discussed in detail in view of the achieved results.}}, author = {{Zdravkov, V. I. and Kehrle, J. and Obermeier, G. and Gsell, S. and Schreck, M. and Müller, C. and Krug von Nidda, H.-A. and Lindner, Jörg and Moosburger-Will, J. and Nold, E. and Morari, R. and Ryazanov, V. V. and Sidorenko, A. S. and Horn, S. and Tidecks, R. and Tagirov, L. R.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{5}}, publisher = {{American Physical Society (APS)}}, title = {{{Reentrant superconductivity in superconductor/ferromagnetic-alloy bilayers}}}, doi = {{10.1103/physrevb.82.054517}}, volume = {{82}}, year = {{2010}}, } @article{4202, abstract = {{Unintentional doping in nonpolar a-plane 112¯0 gallium nitride GaN grown on r-plane 11¯02 sapphire using a three-dimensional 3D–two-dimensional 2D growth method has been characterized. For both 2D only and 3D–2D growth, the presence of an unintentionally doped region adjacent to the GaN/sapphire interface is observed by scanning capacitance microscopy SCM. The average width of this unintentionally doped layer is found to increase with increasing 3D growth time. By using an intentionally doped GaN:Si staircase structure for calibration, it is shown that the unintentionally doped region has an average carrier concentration of 2.50.31018 cm−3. SCM also reveals the presence of unintentionally doped features extending at 60° from the GaN/sapphire interface. The observation of decreasing carrier concentration with distance from the GaN/sapphire interface along these features may suggest that the unintentional doping arises from oxygen diffusion from the sapphire substrate. Low temperature cathodoluminescence spectra reveal emission peaks at 3.41 and 3.30 eV, which are believed to originate from basal plane stacking faults BSFs and prismatic stacking faults PSFs, respectively. It is shown that the inclined features extending from the GaN/sapphire interface exhibit both enhanced BSF and PSF emission. We suggest that enhanced unintentional doping occurs in regions around PSFs. Where BSFs intersect this doped material their emission is also enhanced due to reduced nonradiative recombination. Transmission electron microscopy confirms the presence of PSFs extending through the film at 60° from the GaN/sapphire interface.}}, author = {{Zhu, Tongtong and Johnston, Carol F. and Häberlen, Maik and Kappers, Menno J. and Oliver, Rachel A.}}, issn = {{0021-8979}}, journal = {{Journal of Applied Physics}}, number = {{2}}, publisher = {{AIP Publishing}}, title = {{{Characterization of unintentional doping in nonpolar GaN}}}, doi = {{10.1063/1.3284944}}, volume = {{107}}, year = {{2010}}, } @article{4204, abstract = {{A comparative theoretical investigation of carbon interstitials in silicon is presented. Calculations using classical potentials are compared to first-principles density-functional theory calculations of the geometries, formation, and activation energies of the carbon dumbbell interstitial, showing the importance of a quantummechanical description of this system. In contrast to previous studies, the present first-principles calculations of the interstitial carbon migration path yield an activation energy that excellently matches the experiment. The bond-centered interstitial configuration shows a net magnetization of two electrons, illustrating the need for spin-polarized calculations.}}, author = {{Zirkelbach, F. and Stritzker, B. and Nordlund, K. and Lindner, Jörg and Schmidt, W. G. and Rauls, E.}}, issn = {{1098-0121}}, journal = {{Physical Review B}}, number = {{9}}, publisher = {{American Physical Society (APS)}}, title = {{{Defects in carbon implanted silicon calculated by classical potentials and first-principles methods}}}, doi = {{10.1103/physrevb.82.094110}}, volume = {{82}}, year = {{2010}}, } @inproceedings{4206, author = {{Lindner, Jörg}}, location = {{Universidad Autónoma de Madrid (Spain)}}, title = {{{Advanced topics and applications of Transmission Electron Microscopy, Part I-II}}}, year = {{2010}}, } @book{4207, editor = {{Ila, D. and Kishimoto, N. and Lindner, Jörg and Baglin, J.}}, isbn = {{978-1-60511-154-4}}, location = {{San Francisco (USA)}}, publisher = {{MRS Symposium Proceedings }}, title = {{{Ion Beams and Nano-Engineering}}}, volume = {{1181}}, year = {{2010}}, } @article{4208, abstract = {{Growth of GaN on Si(111) potentially enables cost efficient manufacturing of optoelectronic devices due to the possibility of using cheap large area substrates. However, GaN layers grown on Si(111) substrates suffer from high tensile stress that can lead to cracking at layer thicknesses exceeding 1 μm. Another challenge is the high dislocation density of GaN layers grown on Si(111) which is detrimental to device performance. In this paper we show that a step graded AlGaN buffer layer can compensate tensile stress, avoiding cracking, and at the same time reduce the dislocation density. An additional SiNx interlayer in the GaN layer is shown to further reduce the dislocation density down to the high 108 /cm². Weak beam dark field TEM was used to study the dislocation reduction in cross sectional samples and for comparison of the step graded AlGaN buffer layer structure to a continuously graded one. STEM ADF was used to determine the exact location of dislocation bending with respect to the position of the interface.}}, author = {{Häberlen, M and Zhu, D and McAleese, C and Kappers, M J and Humphreys, C J}}, issn = {{1742-6596}}, journal = {{Journal of Physics: Conference Series}}, publisher = {{IOP Publishing}}, title = {{{Dislocation reduction in MOVPE grown GaN layers on (111)Si using SiNxand AlGaN layers}}}, doi = {{10.1088/1742-6596/209/1/012017}}, volume = {{209}}, year = {{2010}}, }