Photoconductive gain in semiconductor quantum wires (2008)
Rossler, C., Manus, S., Kotthaus, J. P., Holleitner, A. W., Schuh, D., ...
We report on a photoconductive gain in semiconductor quantum wires which are lithographically defined in an AlGaAs/GaAs quantum well via a shallow-etch technique. The effect allows resolving the...
Optoelectronic Sensitization of Individual Carbon Nanotubes by CdTe Nanocrystals (2008)
Zebli, B., Vieyra, H. A., Carmeli, I., Hartschuh, A., Kotthaus, J. P., Holleitner, A. W.
We investigate the photoresponse of individual single-walled carbon nanotube-nanocrystal-hybrids. The nanocrystals are bound to the nanotubes via molecular recognition. We find that the photoresponse...
Dynamic photoconductive gain effect in shallow-etched AlGaAs/GaAs quantum wires (2008)
Rossler, C., Manus, S., Kotthaus, J. P., Holleitner, A. W., Schuh, D., ...
We report on a dynamic photoconductive gain effect in quantum wires which are lithographically fabricated in an AlGaAs/GaAs quantum well via a shallow-etch technique. The effect allows resolving the...
Optically induced transport properties of freely suspended semiconductor submicron channels (2008)
Rossler, C., Manus, S., Ludwig, S., Kotthaus, J. P., Simon, J., ...
We report on optically induced transport phenomena in freely suspended channels containing a two-dimensional electron gas (2DEG). The submicron devices are fabricated in AlGaAs/GaAs heterostructures...
Nonequilibrium interactions between two quantum circuits (2008)
Khrapai, V. S., Ludwig, S., Kotthaus, J. P., Tranitz, H. P., Wegscheider, W.
We briefly overview our recent results on nonequilibrium interactions between neighboring electrically isolated nanostructures. One of the nanostructures is represented by an externally biased...
Nonequilibrium phenomena in adjacent electrically isolated nanostructures (2008)
Khrapai, V. S., Ludwig, S., Kotthaus, J. P., Tranitz, H. P., Wegscheider, W.
We report on nonequilibrium interaction phenomena between adjacent but electrostatically separated nanostructures in GaAs. A current flowing in one externally biased nanostructure causes an...
Micropatterned Electrostatic Traps for Indirect Excitons in Coupled GaAs Quantum Wells (2007)
Gartner, A., Prechtel, L., Schuh, D., Holleitner, A. W., Kotthaus, J. P.
We demonstrate an electrostatic trap for indirect excitons in a field-effect structure based on coupled GaAs quantum wells. Within the plane of a double quantum well indirect excitons are trapped at...
Counterflow of electrons in two isolated quantum point contacts (2007)
Khrapai, V. S., Ludwig, S., Kotthaus, J. P., Tranitz, H. P., Wegscheider, W.
We study the interaction between two adjacent but electrically isolated quantum point contacts (QPCs). At high enough source-drain bias on one QPC, the drive QPC, we detect a finite electric current...
An electrostatically defined serial triple quantum dot charged with few electrons (2007)
Schröer, D., Greentree, A. D., Gaudreau, L., Eberl, K., Hollenberg, L. C. L., Kotthaus, J. P., ...
A serial triple quantum dot (TQD) electrostatically defined in a GaAs/AlGaAs heterostructure is characterized by using a nearby quantum point contact as charge detector. Ground state stability...
A double-dot quantum ratchet driven by an independently biased quantum point contact (2006)
Khrapai, V. S., Ludwig, S., Kotthaus, J. P., Tranitz, H. P., Wegscheider, W.
We study a double quantum dot (DQD) coupled to a strongly biased quantum point contact (QPC), each embedded in independent electric circuits. For weak interdot tunnelling we observe a finite current...
Drift mobility of long-living excitons in coupled GaAs quantum wells (2006)
Gartner, A., Holleitner, A. W., Schuh, D., Kotthaus, J. P.
We observe high-mobility transport of indirect excitons in coupled GaAs quantum wells. A voltage-tunable in-plane potential gradient is defined for excitons by exploiting the quantum confined Stark...
Spectroscopy of molecular states in a few-electron double quantum dot (2006)
Hüttel, A. K., Ludwig, S., Eberl, K., Kotthaus, J. P.
Semiconductor quantum dots, so-called artificial atoms, have attracted considerable interest as mesoscopic model systems and prospective building blocks of the "quantum computer". Electrons are...
Molecular states in a one-electron double quantum dot (2006)
Hüttel, A. K., Ludwig, S., Lorenz, H., Eberl, K., Kotthaus, J. P.
The transport spectrum of a strongly tunnel-coupled one-electron double quantum dot electrostatically defined in a GaAs/AlGaAs heterostructure is studied. At finite source-drain-voltage we...
Molecular states in a one-electron double quantum dot (2005)
Huettel, A. K., Ludwig, S., Lorenz, H., Eberl, K., Kotthaus, J. P.
The transport spectrum of a strongly tunnel-coupled one-electron double quantum dot electrostatically defined in a GaAs/AlGaAs heterostructure is studied. At finite source-drain-voltage we...
Direct control of the tunnel splitting in a one-electron double quantum dot (2005)
Huettel, A. K., Ludwig, S., Eberl, K., Kotthaus, J. P.
Quasi-static transport measurements are employed on a laterally defined tunnel-coupled double quantum dot. A nearby quantum point contact allows us to track the charge as added to the device. If...
Direct control of the tunnel splitting in a one-electron double quantum dot (2005)
Hüttel, A. K., Ludwig, S., Lorenz, H., Eberl, K., Kotthaus, J. P.
Periodic Field Emission from an Isolated Nano-Scale Electron Island (2004)
Scheible, D. V., Weiss, C., Kotthaus, J. P., Blick, R. H.
We observe field emission from an isolated nano-machined gold island. The island is able to mechanically oscillate between two facing electrodes, which provide recharging and detection of the...
Single electron-phonon interaction in a suspended quantum dot phonon cavity (2003)
Höhberger, E. M., Blick, R. H., Brandes, T., Kirschbaum, J., Wegscheider, W., Bichler, M., ...
An electron-phonon cavity consisting of a quantum dot embedded in a free-standing GaAs/AlGaAs membrane is characterized in Coulomb blockade measurements at low temperatures. We find a complete...
Phase coherent transport in two coupled quantum dots (2003)
Blick, R. H., Hüttel, A. K., Holleitner, A. W., Hohberger, E. M., Qin, H., Kirschbaum, I., ...
Quantum dots by now offer a well-defined environment for studying quantum physics. Hence. various proposals have been introduced how to integrate these artificial molecules for building quantum...
Spin blockade in ground-state resonance of a quantum dot (2003)
Hüttel, A. K., Qin, H., Holleitner, A. W., Blick, R. H., Neumaier, K., Weinmann, D., ...
Probing and controlling the bonds of an artificial molecule (2002)
Holleitner, A. W., Blick, R. H., Hüttel, A. K., Eberl, K., Kotthaus, J. P.
We demonstrate how molecular quantum states of coupled semiconductor quantum dots are coherently probed and manipulated in transport experiments. The applied method probes quantum states by the...
Aharonov-Bohm oscillations for charge transport through two parallel quantum dots (2002)
Holleitner, A. W., Qin, H., Blick, R. H., Eberl, K., Kotthaus, J. P.
We observe Aharonov-Bohm oscillations in an interferometer containing one quantum dot in each arm. The two quantum dots are laterally defined in a two-dimensional electron gas and are both brought to...
Spin blockade in ground state resonance of a quantum dot (2001)
Huettel, A. K., Qin, H., Holleitner, A. W., Blick, R. H., Neumaier, K., Weinmann, D., ...
We present measurements on spin blockade in a laterally integrated quantum dot. The dot is tuned into the regime of strong Coulomb blockade, confining ~ 50 electrons. At certain electronic states we...
Edge and bulk effects in the Terahertz-photoconductivity of an antidot superlattice (2000)
Jager, B. G. L., Wimmer, S., Lorke, A., Kotthaus, J. P., Wegscheider, W., Bichler, M.
We investigate the Terahertz(THz)-response of a square antidot superlattice by means of photoconductivity measurements using a Fourier-transform-spectrometer. We detect, spectrally resolved, the...
Nonlinear acousto-electric transport in a two-dimensional electron system (2000)
Govorov, A. O., Kalameitsev, A. V., Rotter, M., Wixforth, A., Kotthaus, J. P., Hoffmann, K. H., ...
We study both theoretically and experimentally the nonlinear interaction between an intense surface acoustic wave and a two-dimensional electron plasma in semiconductor-piezocrystal hybrid...
Determination of the complex microwave photoconductance of a single quantum dot (2000)
Qin, H., Simmel, F., Blick, R. H., Kotthaus, J. P., Wegscheider, W., Bichler, M.
A small quantum dot containing approximately 20 electrons is realized in a two-dimensional electron system of an AlGaAs/GaAs heterostructure. Conventional transport and microwave spectroscopy reveal...
Fertig, N., Tilke, A., Blick, R. H., Kotthaus, J. P., Behrends, J. C., Bruggencate, G. Ten
We investigate the microscopic contact of a cell/semiconductor hybrid. The semiconductor is nanostructured with the aim of single channel recording of ion channels in cell membranes. This approach...
Microwave spectroscopy on a double quantum dot with an on-chip Josephson oscillator (1999)
Holleitner, A. W., Qin, H., Simmel, F., Irmer, B., Blick, R. H., Kotthaus, J. P., ...
We present measurements on microwave spectroscopy on a double quantum dot with an on-chip microwave source. The quantum dots are realized in the two-dimensional electron gas of an AlGaAs/GaAs...
Spectroscopy of nanoscopic semiconductor rings (1999)
Lorke, A., Luyken, R. J., Govorov, A. O., Kotthaus, J. P., Garcia, J. M., Petroff, P. M.
Making use of self-assembly techniques, we demonstrate the realization of nanoscopic semiconductor quantum rings in which the electronic states are in the true quantum limit. We employ two...
Shashkin, A. A., Dolgopolov, V. T., Deviatov, E. V., Irmer, B., Haubrich, A. G. C., Kotthaus, J. P., ...
We study the lateral tunneling through the gate-voltage-controlled barrier, which arises as a result of partial elimination of the donor layer of a heterostructure along a fine strip using an atomic...
Statistics of the Coulomb blockade peak spacings of a silicon quantum dot (1999)
Simmel, F., Abusch-Magder, David, Wharam, D. A., Kastner, M. A., Kotthaus, J. P.
We present an experimental study of the fluctuations of Coulomb blockade peak positions of a quantum dot. The dot is defined by patterning the two-dimensional electron gas of a silicon MOSFET...
Submicron contact printing on silicon using stamp pads. (1999)
Pompe, T., Fery, A., Herminghaus, S., Kriele, A., Lorenz, H., Kotthaus, J. P.
Anomalous Kondo-effect in Quantum Dot at non-zero bias (1998)
Simmel, F., Blick, R. H., Kotthaus, J. P., Wegscheider, W., Bichler, M.
We present measurements on the Kondo-effect in a small quantum dot connected strongly to one lead and weakly to the other. The conductance of the dot reveals an offset of the Kondo resonance at zero...
Nano-ploughed Josephson Junctions as on-chip Radiation Sources (1998)
Irmer, B., Simmel, F., Blick, R. H., Lorenz, H., Kotthaus, J. P., Bichler, M., ...
A new technique is presented which enables the fabrication of highly transparent Josephson junctions in combination with mesoscopic devices. We utilize a modified AFM tip to plough grooves into...
Air as an Adjustable Insulator for C-V and G-V Analysis of Semiconductor Surfaces. (1998)
Moreland,J., Drucker,J., Hansma,P. K., Kotthaus,J. P., Adams,A.
An adjustable metal-air-semiconductor capacitor was fabricated using a Pb disk suspended 1700 - 3600 A above an n-type surface. Experimental differential capacitance versus voltage and differential...
Josephson Junctions defined by a Nano-Plough (1998)
Irmer, B., Blick, R. H., Simmel, F., Goedel, W., Lorenz, H., Kotthaus, J. P.
We define superconducting constrictions by ploughing a deposited Aluminum film with a scanning probe microscope. The microscope tip is modified by electron beam deposition to form a nano-plough of...
Irmer, B., Kehrle, M., Lorenz, H., Kotthaus, J. P.
We study local oxidation induced by dynamic atomic force microscopy (AFM), commonly called TappingMode AFM. This minimizes the field induced forces, which cause the tip to blunt, and enables us to...
Parallel Quantum-Point-Contacts as High-Frequency-Mixers (1997)
Haubrich, A. G. C., Wharam, D. A., Kriegelstein, H., Manus, S., Lorke, A., Gossard, A. C., ...
We present the results of high-frequency mixing experiments performed upon parallel quantum point-contacts defined in the two-dimensional electron gas of an Al_{x}Ga_{1-x}As/GaAs-heterostructure. The...
Lateral superlattices as voltage-controlled traps for excitons (1997)
Zimmermann, S., Govorov, A. O., Hansen, W., Kotthaus, J. P., Bichler, M., Wegscheider, W.
We demonstrate the localisation of quantum well excitons in a periodic array of linear traps using photoluminescence experiments. The excitonic traps are induced by applying spatially alternating...
Acoustically driven storage of light in a quantum well (1997)
Rocke, C., Zimmermann, S., Wixforth, A., Kotthaus, J. P., Boehm, G., Weimann, G.
The strong piezoelectric fields accompanying a surface acoustic wave on a semiconductor quantum well structure are employed to dissociate optically generated excitons and efficiently trap the created...
Far-infrared and capacitance spectroscopy of self-assembled InAs quantum dots (1996)
Lorke, A., Fricke, M., Miller, B. T., Haslinger, M., Kotthaus, J. P., Medeiros-Ribeiro, G., ...
We review a number of recent experiments which are probing ground state and excitations of few-electron systems in self-assembled InAs quantum dots. Far-infrared spectroscopy, together with local as...
Single-electron charging of self-assembled InAs quantum dots (1996)
Fricke, M., Lorke, A., Haslinger, M., Kotthaus, J. P., Medeiros-Ribeiro, G., Petroff, P. M.
The many-particle ground state and excitations of self-assembled InAs quantum dots are investigated using far-infrared (FIR) and capacitance spectroscopy. The contributions of quantization and...
Shell structure and electron-electron interaction in self-assembled InAs quantum dots (1996)
Fricke, M., Lorke, A., Kotthaus, J. P., Medeiros-Ribeiro, G., Petroff, P. M.
Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1
Acousto-optic effects of surface acoustic waves in semiconductor quantum well structures (1996)
Rocke, C., Wixforth, A., Kotthaus, J. P., Boehm, H., Weimann, G.
We report on recent experiments investigating the modification of the inter-band optical response of a piezoelectric semiconductor quantum well structure under the influence of intense short period...