Nicolas Forrer (2020-2024)

Germanium/Silicon Nanowire Heterostructures for Quantum Computing

Nanowires and their synthesis have gained increasing interest as nanosized building blocks for functional devices, due to their tuneable and fascinating properties. The compatibility of silicon and germanium with complementary metal oxide semiconductor technology makes them highly attractive. Combining the two materials to germanium-silicon core-shell nanowires provides optimal candidates for quantum applications due to their outstanding characteristics of absent nuclear spin, long coherence times, high spin-orbit coupling, strong confinement of holes, high carrier mobility of germanium at room temperature and high quality silicon dioxide. To foster these properties, high quality nanowires are needed. Chemical vapour deposition techniques provide the necessary control over the dimension, the crystal phase, and the crystallographic orientation. [...]

Giulio de Vito (2020-2024)

Four terminal devices for anisotropic thermal transport experiments

The investigation of heat flow in nanostructures and low-dimensional system is one of the major challenge in microtechnology. However, the deviation of miniaturization trend of transistors fromtheMoore’s law indicates the increasing importance of an effective thermal management of microdevices. Therefore, the examination of the heat properties of different nano-size materials is paving the way for more efficient microchips. To guide these efforts, it is of uttermost importance to characterize the intrinsic properties of the materials with a consistent and reliable method with a high signal-to-noise ratio. To meet these requirements, a novel four-terminal device is proposed which involves fabricating suspended four transducers, which can act as thermometer as well as heater, combined with the suspension of a two-dimensional material. In this work, we present the fabrication and characterization of a device designed to measure the in-plane thermal properties of nanomaterials in multiple directions. Additionally, the device allows to perform electrical and optical measurements simultaneously. This allows to spatially resolve eventual thermal property anisotropies and the correction of measurements by accounting for the contact resistances.

Yashpreet Kaur (2019-2023)

Thermal rectification in designed nanowires

Diego de Matteis (2018-2023)

Phonon engineering in nanowire heterostructures

The exploitation of unique optoelectronic, mechanical, and thermal properties of nanostructured materials has a long history, even antecedent its deep understanding and systematic investigation. Indeed, the high surface-to-volume ratio of nanostructures, together with the possibility of quantum confinement, results in interesting behaviors for optoelectronic, thermoelectric, biomedical, and many more applications. Moreover, it allows the realization of material systems that would be extremely taxing or impossible to obtain in bulk form. Whatever the application, the operation of any device poses challenges in terms of heat management and energy efficiency.

Lukas Gubser (2017-2021)

Phonon detection by double quantum dots

During the last few decades research has improved our knowledge and control over electrons and photons, enabling impressing advances for electronic and optoelectronic applications. The same degree of control is still lacking for phonons. The ability to manipulate phonons and phonon transport on a quantum level would lead to full control over heat flow in nanodevices. Beside improving thermoelectric devices, doing a part to solve the global energy crisis, and solving the thermal management bottlenecks affecting computer chips and data storage technologies, it could also lead to phonon transistors and the realization of phonon logic gates.

Medina Umar (2016-2020)

Deposition and Characterization of Wide Band Gap P-Type Metal Oxides for Photovoltaic Applications

Daily, the population in the world is increasing, along with the quantity of needed energy. However, the fossils are running out and climate change is a global concern now, thus, the demand for alternative energies is growing. Solar energy comes free by the sun light and, if well harvested, it could be a valuable and readily available alternative source of energy for humanity. In this work, we perform deposition and characterization of thin films of copper oxides to be used in photovoltaic devices.