Master’s and Bachelor’s Thesis Projects

Group-III nitrides are at the heart of modern electronics, optoelectronics, and acoustic devices. This project explores a promising new member of the family: chromium aluminum nitride, or (Cr,Al)N. By incorporating chromium into the hexagonal AlN lattice, this material may combine piezoelectric and ferromagnetic properties — an unusual pairing that could open the door to new multifunctional device concepts. The student will use plasma-assisted molecular beam epitaxy (PAMBE) to grow (Cr,Al)N films on Si and SiC substrates and characterize them using XRD, AFM, RHEED, and XPS. The goal is to map out the growth conditions under which the hexagonal phase is stable — fundamental knowledge that does not yet exist for this material system. ... read more

Graphene consists of a single layer of carbon atoms arranged in hexagonal lattice and represents an excellent platform for two dimensional materials with huge potentials in electronics and quantum technology. Structural defects in graphene can be deliberately introduced in the honeycomb network.

In this project the objective will be to investigate artificial defects of graphene and defect-metal interaction using low temperature scanning tunneling microscopy. ... read more

2D-Materials have gained tremendous attention, at the latest, since the Nobel price was awarded to A. Geim and K. Novoselov in 2010 for the isolation and investigation of single layer graphite, “graphene”, which was theoretically predicted to be thermodynamically instable. Ever since, many other layered structures have been identified and their single-layered crystals isolated and studied.

In this project we aim to investigate the heterostructures created from magnetic and non-magnetic layered materials. ... read more

Raman spectroscopy has become a standard in many fields including quality control in the semiconductor or food industries, is widely used for drug or explosives screenings and finds its way into medical applications where e.g. non-invasively skin cancer tests can be carried out without taking tissue samples. A strength of this method is to be sensitive to the symmetry of materials, i.e. the sample’s (crystallographic) structure, and hence also be sensitive to changes in this material’s property.

The project is split into two parts: i) to finalize the finetuning of the metrology and develop a measure for its uncertainty and ii) to investigate different complex oxide-perovskites with chemical formula ABO3, which can have phase transitions of different order (structural, spin, …). The aim of the second part is to further the understanding of the material’s microscopic order, leading to macroscopic effects, such as magnetism or ferroelectricity. ... read more

Two-dimensional (2D) materials provide a versatile platform for exploring novel spintronic device concepts with potential applications in future information technologies. In recent years, 2D spintronics has therefore attracted significant interest in condensed matter physics. In this context, the Paul-Drude Institut (PDI) has demonstrated the growth of high-quality, large-area, all-epitaxial 2D heterostructures, such as Fe5GeTe2/Graphene [H. Lv et al., Small, 2023], providing a strong foundation for 2D spintronic device investigations.

In this project, the student will develop lateral spin valve devices based on MBE-grown Fe5GeTe2/Graphene heterostructures. The work will focus on optimizing cleanroom fabrication processes, realizing functional devices, and investigating their magnetotransport properties, with particular emphasis on room-temperature operation. ... read more

Ferrimagnetic spintronics combines the advantages of ferromagnetic and antiferromagnetic materials and has become a highly promising research field in modern condensed-matter physics. In particular, ferrimagnets offer exciting opportunities for next-generation data storage technologies, enabling ultrafast operation and ultrahigh storage density.
In this project, the student will explore the ferrimagnetic material NiCo2O4 (NCO), which exhibits strong perpendicular magnetic anisotropy at room temperature. The main objective is to synthesize high-quality thin films using molecular beam epitaxy (MBE) and investigate their structural, magnetic and transport properties. ... read more

Layered magnets can be seen as ideal platforms for exploring magnetism in the 2D limit. To establish their potential in future technologies, the realization of high-quality magnetic layered materials exhibiting ferromagnetism (FM) and/or antiferromagnetism close to room temperature is urgently needed. Recently, we have successfully synthesized at wafer-scale using molecular beam epitaxy on the one hand side a metastable α-FeGe2 layered phase (not found as a bulk material) and on the other hand side layered Fe5GeTe2 as well as Fe3GaTe2 films.

The aim of the project is to investigate the magnetic properties and to establish the magnetic phase diagram of α-FeGe2 and/or Fe5GeTe2 (Fe3GaTe2) films. In principle, there is room for two individual projects. ... read more

III-V semiconductor quantum dots (QDs) are the purest single photon sources at cryogenic temperatures. Their emission rate and directionality can be improved by placing them in a photonic environment such as a microcavity (MC) and taking advantage of the Purcell effect. However, the matching of the QD energy with that of the MC is challenging, especially for high-Q MCs.

The main objective of the project is to demonstrate dynamic Purcell effect and GHz-triggered single photon emission in patterned MCs with III-V QDs. ... read more

Transfer of information between GHz qubits and near-infrared photons can be done via piezoelectrically excited phonons, which can enable efficient microwave-to-optical conversion for scalable networks of quantum computers. We have shown that one novel approach is to use semiconductor microcavities (MCs) which provide efficient coupling between quantum well excitons and bulk acoustic waves (BAWs) injected by electrically driven bulk acoustic resonators (BARs) fabricated on top of MC.

The main objective of the project is to develop the fabrication process for the transparent bulk acoustic resonators (BARs) with ITO contacts for the excitation of 5-20 GHz acoustic waves in semiconductor heterostructures. ... read more

There is an increasing interest in coupling the dynamic strain of surface acoustic waves (SAWs) to electrical excitations in semiconductor heterostructures containing 2D materials to acoustically manipulate their optoelectronic properties. While optical phenomena in 2D nanostructures can be conveniently mapped by photoluminescence, local probing of mechanical properties remains challenging.

The goal of this project is to spatially probe the SAW profile in semiconductor heterostructures containing 2D materials using atomic-force microscopy (AFM). ... read more