Technische Physik


    The physics of quantum transport and its application in novel nanoelectronic device concepts represent main activities of our research. By tailoring nanoelectronic properties the functioning for a given number of basic switching were enhanced. Based on monolithic designs we focus on the development of:

    • Nanoelectronic logics
    • Single quantum dot memories
    • Mesoscopic sensors

    Electron microscope image of a full adder functioning at room temperature, which was realized by monolithically interconnected quantum wires and Y-branched junctions in a modulation doped GaAs/AlGaAs heterostucture.

    Our work is engaged with robust ballistic transport realized by electron beam lithography and wet chemical etching of GaAs/AlGaAs heterostructures structures. In order to utilize ballistic transport even at room temperature shallow electron gases are laterally structured and narrow conducting channels only a few 10 nm wide are monolithically interconnected.

    Research Topics

    To find out more about Nanoelectronics' research areas, explore the following topics:

    Transition metal oxide heterostructures (TMOs) are fascinating material combinations which can exist in different chemical and crystalline structures, each having fascinating physical properties spanning from ferroelectricity, magnetism, high-temperature superconductivity to colossal magnetoresistance. Complex TMOs offer a broad variety of research themes by tailoring their interfaces with atomic precision and the complex interactions between spin, charge and orbital degrees of freedom. Charge transfer, electrostatic coupling, symmetry breaking, frustration and strain enable the observation of different physical phenomena, e.g. the electrical properties in such heterostructures can be tuned from insulating to conducting to superconducting. The rich complexity and variety makes TMO-based devices interesting for integrated devices in state-of-the-art electronic circuits, e.g. complex oxide-based field effect transistors and ring oscillators, or for environmental monitoring. Complex TMOs also offer the potential to be employed for future information and quantum information processing (oxide spintronics and topological insulators). The broad spectrum of complex oxides based applications emerges from their crystalline structure and through the breaking of fundamental symmetries at their interfaces. We are interested in the rich physics offered by these materials and our research is centered around the fabrication of highest quality transition metal oxide heterostructures with precise interface engineering by molecular beam epitaxy. The field of TMO heterostructures now emerges into an exciting research field, in which further tuning their exceptional properties give insights to hidden phases and emergent physical phenomena.

    Impedance matching networks and techniques are developed for the investigation of the high frequency properties in nanoelectronic circuits like:

    • Microwave rectifiers
    • Counter devices
    • Nanoelectronic transistors

    In nonlinear mesoscopic transport the quantum capacitance dominates the  switching properties. As a result internal feedback, steep thresholds, and noise-induced switching occur, which we are utilizing for:

    • Self-gating
    • Stochastic resonance
    • Magnetoasymmetries

    Novel memories based on self-assembled quantum dots in conjunction with nanoscaled transistors were developed. In such devices Coulomb rectification and single electron floating gate operation were observed and applied for the realization of a single quantum dot flash memory.