Current Thesis Topics

Cubic gallium nitride (GaN) is a promising material for high-frequency and optoelectronic devices due to its superior electronic properties and reduced polarization effects compared to its hexagonal counterpart. However, growing high-quality cubic GaN is challenging.

The primary goal of this project is to develop a process for growing high-quality cubic GaN on 3C-SiC/Si(001). The project will involve plasma-assisted molecular beam epitaxy (MBE) for material growth and advanced characterization techniques for structural and morphological analysis. ... read more

The strain field by a single dislocation can be calculated based on text-book knowledge, however, more complex arrangements usually require numerical approaches. Numerical extended finite element methods (XFEM) may serve as a versatile tool to consider highly realistic geometries and full elastic anisotropy (particularly in 2D layered materials or materials with low crystal symmetry or high anisotropy).

The objective of this project is to create XFEM cases for single and multiple dislocation arrangements in various crystallographic systems (e.g., isotropic, cubic and trigonal) and compare results to analytical calculations. ... 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

Diamond Isn’t Just for Jewelry — It’s the Future of Quantum Tech!
From quantum sensors to qubits, diamond’s unmatched properties — extreme hardness, biocompatibility
radiation resistance, and record-breaking thermal conductivity — make it a superstar material for next-gen
technologies. But growing diamond sustainably, and at low pressure, is a game-changer. This thesis
explores how carbon atoms turn into diamonds in liquid metal systems, using atomistic simulations to
uncover the atomic magic behind a process that could reshape the future of quantum materials. ... read more

The use of piezoelectric III-nitride nanowires is promising for the application in flexible piezoelectric energy harvesting. However, conventionally applied GaN and AlN nanowires provide rather low output signals. One way to improve the piezoelectric response of III-nitrides is to alloy them with transition metal nitrides, with ternary (Al,Sc)N being the archetypal example exhibiting five times the piezoelectricity of AlN. Nevertheless, fabricating (Al,Sc)N nanowires with a well-controlled morphology on large scale remains challenging.

The aim of this thesis is the development of top-down (Al,Sc)N nanowires with well-controlled morphology and evaluate them for the application in energy harvesting. ... read more

The performance of optoelectronic devices—such as light-emitting diodes, laser diodes, and photodetectors—critically depends on the structural quality of the III-V semiconductor materials used in their active layers. High crystalline perfection is essential to achieve superior electrical and optical performance.

This project aims to develop and optimize nanostructure fabrication on GaN substrates to support high-quality epitaxial growth of III-V semiconductors. The work will focus both the fabrication of nanostructure with controlled dimention and their morphological characterization. ... 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

The efficient manipulation of magnetic nanostructures is fundamental for high-capacity memory, computing, and magnetic sensing applications. Conventional manipulation techniques based on magnetic fields and electric currents typically cause energy dissipation and limit miniaturization. In contrast, strain-based magnetization control is a promising alternative that can lead to fast, compact, and energy-efficient devices.

The aim of this project is to investigate the magnetization dynamics of epitaxial multilayers under SAW strain fields. ... read more

Magnetic two-dimensional (2D) materials are very promising building blocks for the realization of ultra-compact and innovative spintronic devices. However, most of the 2D magnets explored so far exhibit magnetic transition temperatures well below 300 K, which hinders applications.

This project aims at the investigation of the structural properties of ultrathin ... read more

The efficient manipulation of magnetic nanostructures is fundamental for applications such as high-capacity memory, computing, and sensing devices. In this context, 2D ferromagnetic materials are expected to play a crucial role in future spin-based devices (e.g., spin valves and random-access magnetic memories) with high energy efficiency and ultracompact dimensions.

The aim of this project is to analyze magnetic textures in epitaxial FGT films using magnetooptical Kerr (MOKE) microscopy. ... 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

Defects are not always bad! Optically active defect centers in solids can play an important role in quantum technology. For example, they can act as single-photon sources and spin memories. Of particular interest are optically addressable spin centers, i.e. defect centers whose electronic spin states can be selectively initialized and read out with light.

The goal of this project is to control the spin dynamics of VSi centers in the 6H-SiC polytype using SAWs. Specifically, we aim at the acoustic spin manipulation of the V3 center, which is promising for the implementation of robust spin–photon entanglement schemes. ... 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