Memory effect of Mn$_5$Ge$_3$ nanomagnets embedded inside a Mn-diluted Ge matrix (2009)
Zhou, Shengqiang, Shalimov, Artem, Potzger, Kay, Jeutter, Nicole M., Baehtz, Carsten, Helm, Manfred, ...
Crystalline Mn5Ge3 nanomagnets are formed inside a Mn-diluted Ge matrix using Mn ion implantation. A temperature-dependent memory effect and slow magnetic relaxation are observed below the...
Anomalous Hall resistance in Ge:Mn systems with low Mn concentrations (2009)
Zhou, Shengqiang, Buerger, Danilo, Helm, Manfred, Schmidt, Heidemarie
Taking Mn doped Germanium as an example, we evoke the consideration of a two-band-like conduction in diluted ferromagnetic semiconductor (FMS). The main argument for claiming Ge:Mn as a FMS is the...
Spin-dependent transport in nanocomposite C:Co films (2009)
Zhou, Shengqiang, Berndt, Markus, Buerger, Danilo, Heera, Viton, Potzger, Kay, Abrasonis, Gintautas, ...
The magneto-transport properties of nanocomposite C:Co (15 and 40 at.% Co) thin films are investigated. The films were grown by ion beam co-sputtering on thermally oxidized silicon substrates in the...
Ferromagnetic, structurally disordered ZnO implanted with Co ions (2008)
Potzger, Kay, Zhou, Shengqiang, Xu, Qingyu, Shalimov, Artem, Groetzschel, Rainer, Schmidt, Heidemarie, ...
We present superparamagnetic clusters of structurally highly disordered Co-Zn-O created by high fluence Co ion implantation into ZnO (0001) single crystals at low temperatures. This secondary phase...
Room temperature ferromagnetism in carbon-implanted ZnO (2008)
Zhou, Shengqiang, Xu, Qingyu, Potzger, Kay, Talut, Georg, Groetzschel, Rainer, Fassbender, Juergen, ...
Unexpected ferromagnetism has been observed in carbon doped ZnO films grown by pulsed laser deposition [Phys. Rev. Lett. 99, 127201 (2007)]. In this letter, we introduce carbon into ZnO films by ion...
Stehr, Dominik, Winnerl, Stephan, Helm, Manfred, Dekorsy, Thomas, Roch, Tomas, Strasser, Gottfried
The picosecond dynamics of electrons in a doped GaAs/AlGaAs superlattice have been investigated by pump-probe experiments using an infrared free-electron laser. We observe a fast bleaching of the...
Silicon-on-insulator microcavity light emitting diodes with two Si/SiO2 Bragg reflectors (2006)
Potfajova, Jaroslava, Sun, Jiaming, Schmidt, Bernd, Dekorsy, Thomas, Skorupa, Wolfgang, Helm, Manfred
Light emitting pn-diodes were fabricated on a 5.8 μm thick n-type Si device layer of a silicon-on-insulator (SOI) wafer using standard silicon technology and boron implantation. The thickness of...
Tribuzy, Christiana Villas-Bôas, Ohser, Sabine, Winnerl, Stephan, Grenzer, Jörg, Schneider, Harald, Helm, Manfred, ...
Intersubband relaxation dynamics in InGaAs/AlAsSb multiquantum wells (QWs) is studied by single-color femtosecond pump-probe measurements. At early delay times, all samples show an exponential decay...
High-resolution THz spectrometer with kHz scan rates (2006)
Bartels, Albrecht, Thoma, Arne, Janke, Christof, Dekorsy, Thomas, Dreyhaupt, Andre, Winnerl, Stephan, ...
We demonstrate a rapid scanning high-resolution THz spectrometer capable of acquiring THz field transients with 1 ns duration without mechanical delay line. The THz spectrometer is based on two 1-GHz...
Dreyhaupt, Andre, Winnerl, Stephan, Helm, Manfred, Dekorsy, Thomas
We report the impulsive generation of terahertz (THz) radiation with a field amplitude of more than 1.5 kV/cm at megahertz repetition rates, using an interdigitated photoconducting device. The...
High-intensity terahertz radiation from a microstructured large-area photoconductor (2005)
Dreyhaupt, Andre, Winnerl, Stephan, Dekorsy, Thomas, Helm, Manfred
We present a planar large-area photoconducting emitter for impulsive generation of terahertz (THz) radiation. The device consists of an interdigitated electrode metal-semiconductor-metal (MSM)...
Bright green electroluminescence from Tb 3+ in silicon metal-oxide-semiconductor devices (2005)
Sun, Jiaming, Skorupa, Wolfgang, Dekorsy, Thomas, Helm, Manfred, Rebohle, Lars, Gebel, Thoralf
Bright green electroluminescence with luminance up to 2800 cd/m² is reported from indium-tin-oxide/SiO2:Tb/Si metal-oxide-semiconductor devices. The SiO2:Tb3+ gate oxide was prepared by thermal...
Near-infrared intersubband transitions in InGaAsAlAsInAlAs double quantum wells (2005)
Semtsiv, Mykhaylo P., Ziegler, Mathias, Masselink, William Ted, Georgiev, Nikolai, Dekorsy, Thomas, Helm, Manfred
Intersubband optical transitions at short wavelengths in strain-compensated In0.70Ga0.30AsAlAs double quantum wells are investigated by means of mid-infrared absorption. Trade-offs between...
Rare earth ion implantation for silicon based light emission : from infrared to ultraviolet (2005)
Skorupa, Wolfgang, Sun, Jiaming, Prucnal, Slawomir, Rebohle, Lars, Gebel, Thoralf, Nazarov, Alexei N., ...
Using ion implantation different rare earth luminescent centers (Gd3+, Tb3+, Eu3+, Ce3+, Tm3+, Er3+) were created into the silicon dioxide layer of a purpose-designed Metal Oxide Silicon (MOS)...
Efficient silicon based light emitters (2005)
Helm, Manfred, Sun, Jiaming, Potfajova, Jaroslava, Dekorsy, Thomas, Schmidt, Bernd, Skorupa, Wolfgang
Recent progress on electrically driven silicon based light emitters is reviewed, with emphasis on our work on light emitting pn diodes (LED) and MOS devices doped with rare-earth elements. The LEDs...
Light-emitting silicon pn diodes (2004)
Dekorsy, Thomas, Sun, Jiaming, Skorupa, Wolfgang, Schmidt, Bernd, Helm, Manfred
We report on the electrical and optical characteristics of silicon light-emitting pn diodes. The diodes are prepared by ion implantation of boron at high doses and subsequent hightemperature...
Silicon-based electrically driven microcavity LED (2004)
Potfajova, Jaroslava, Sun, Jiaming, Winnerl, Stephan, Dekorsy, Thomas, Skorupa, Wolfgang, Schmidt, Bernd, ...
A silicon pn-diode was embedded into a microcavity composed of a buried metal silicide as bottom reflector and a Si/SiO2 Bragg mirror as top reflector. Spectral narrowing and an increased intensity...
Increased terahertz emission from thermally treated GaSb (2004)
Winnerl, Stephan, Sinning, Steffen, Dekorsy, Thomas, Helm, Manfred
We report on the terahertz (THz) emission from GaSb surfaces with modified surface stochiometry. While very weak emission is observed from virgin GaSb wafers, the emission is significantly increased...
Sun, Jiaming, Skorupa, Wolfgang, Dekorsy, Thomas, Helm, Manfred, Rebohle, Lars, Gebel, Thoralf
Strong ultraviolet electroluminescence with an external quantum efficiency above 1% is observed from an indium-tin oxide/SiO2:Gd/Si metaloxidesemiconductor structure. The SiO2:Gd active layer is...
First lasing of the ELBE MID-IR FEL (2004)
Michel, Peter, Gabriel, Frank, Grosse, Eckart, Evtuschenko, Pavel, Dekorsy, Thomas, Krenz, Marcel, ...
First lasing of the mid-infrared free-electron laser at ELBE was achieved on May 7, 2004. The Radiation Source ELBE at the Forschungszentrum Rossendorf in Dresden is currently under transition from...
Sun, Jiaming, Dekorsy, Thomas, Skorupa, Wolfgang, Schmidt, Bernd, Mücklich, Arndt, Helm, Manfred
The origin of two luminescence bands with maxima around 1.05 eV and 0.95 eV is studied in silicon pn diodes prepared by boron implantation. The two peaks are related to the formation of p-type doping...
Bound-exciton-induced current bistability in a silicon light-emitting diode (2003)
Sun, Jiaming, Dekorsy, Thomas, Skorupa, Wolfgang, Schmidt, Bernd, Helm, Manfred
A bound-exciton-induced current bistability is observed under forward bias in an efficient silicon light-emitting diode at low temperatures. Two stable states of the S-type differential conductivity...
Sun, Jiaming, Dekorsy, Thomas, Skorupa, Wolfgang, Schmidt, Bernd, Helm, Manfred
Efficient electroluminescence with power efficiency up to 0.12% is observed from silicon pn diodes prepared by boron implantation with boron concentrations above the solubility limit at the...
Georgiev, Nikolai, Dekorsy, Thomas, Eichhorn, Frank, Helm, Manfred, Semtsiv, Mykhaylo P., Masselink, William Ted
We have studied intersubband absorption in strain compensated InxGa1xAs/AlAs/InyAl1yAs multiple quantum wells and superlattices grown on InP. X-ray diffraction shows that the layers are...
Infrared-PhononPolariton Resonance of the Nonlinear Susceptibility in GaAs (2003)
Dekorsy, Thomas, Yakovlev, Vladislav A., Seidel, Wolfgang, Helm, Manfred, Keilmann, Fritz
Nonlinear probing of the fundamental lattice vibration of polar crystals is shown to reveal insight into higher-order cohesive lattice forces. With a free-electron laser tunable in the far infrared...
Hot Electron Emission in Semiconductors. (2002)
Gornik, E., Christanell, Robert, Helm, Manfred, Unterrainer, Karl
Sub micron sinusoidal gratings were prepared on GaAs/GaAlAs heterostructures. Experiments to demonstrate a Smith-Purcell-effect in a semiconductor are in preparation. FIR emission due to streaming of...
Characteristic features of the pseudogap and superconducting states of YBa2Cu3O7-x (2002)
Misochko, Oleg V., Georgiev, Nikolai, Dekorsy, Thomas, Helm, Manfred
The relaxation dynamics of the lattice and low-energy quasiparticles in a YBa2Cu3O7−x superconductor are studied by the light reflection technique with femtosecond temporal resolution in a wide...
Misochko, Oleg Victor, Georgiev, Nikolai, Dekorsy, Thomas, Helm, Manfred
We have investigated the temperature dependence of the optical reflectivity on a femtosecond scale in a near optimally doped YBa2Cu3O7-δ superconductor. The combined study of the lattice and...
Hot Electron Emission in Semiconductors. (1998)
Gornik, Erich, Unterrainer, Karl, Helm, Manfred
The spectrum of the simulated far infrared emission from p-Germanium in crossed electric and magnetic fields is studied by means of a tunable narrow-band GaAs-detector. A multimode spectrum is...
Helm, Manfred, Unterrainer, Karl
5TH International Conference on Intersubband Transitions in Quantum Wells. ITWQW'99. Program and Abstracts. 7-11 September 1999, Bad Ischl, Austria. The scope of the conference will cover all...
Helm, Manfred, Unterrainer, Karl
This volume contains papers presented at the 5th International Conference on Intersubband Transitions in Quantum Wells (ITQW'99) held 7-11 September in Bad Ischl, Austria. The field of intersubband...
Potsdam, Pädag. Hochsch., Diss. B., 1971. (Nicht f. d. Austausch.).
Leuna-Merseburg, T. H. f. Chemie, F. f. Verfahrenstechnik u. Grundlagenwiss., Diss. v. 28. Aug. 1964 (Nicht f. d. Aust.).