We offer Bachelor and Master projects in all of our research areas.
If you are willing to write your thesis with us, please get in touch with the contact person of the field you are interested in.
Prof. Dr. Sven Höfling's research interests are related to the design, growth, fabrication and characterization of low dimensional photonic and electronic systems. His expertise includes semiconductor nanostructures and their interaction with light, involving III-V quantum wells and quantum dots, organic semiconductors, high-quality factor microcavities, photonic crystal devices, semiconductor lasers, organic semiconductors and transition metal dichalcogenides.
University of Würzburg
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We are interested in the properties of individual optical micro-resonators and lasers as well as in their coupling with one another. Coupled optical resonator network and lattices are used to realized intricate optical band structures, emulating e.g. graphene physics in an optical system. By precisely tailoring the coupling properties we can realize topological non-trivial structures. We are then able to study the unique properties and the exciting potential of topological polaritons and topological lasers. Here, we are working within the Würzburg-Dresden cluster of excellency ct.qmat. The platforms used for the realization of our samples range from group III-V semiconductirs such as GaAs to fluorescent proteins and transition metal dichalcogenides.
We constantly offer Bachelor and Master theses dealing with a relevant subtopic of the above mentioned projects.
Here are some examples:
- Polariton propagation in honeycomb lattices and nanoribbons
- Optical study of light-matter interaction in organic mCherry/eGFP microcavities
- Design and interface optimization of topological VCSEL lasers
You are kindly invited to send an email and I will try to find a project that can meet your interest. After that, we can discuss a possible project face-to-face or via zoom.
The III-V semiconductors InAs, GaSb and AlSb form the so called 6.1 Angstrom family. Devices based on this material system offer unprecedented electro-optical properties and flexibilities. Depending on the material composition and heterostructure layout, band gap energies and band alignments can be tuned in a wide range opening the path to tailor optical and electronic properties on demand. As a result, devices composed of these semiconducting materials can be used for various applications including high-speed electronics and opto-electronics, gas sensing and thermal imaging.
Our group works on different opto-electronic devices that utilize the properties and flexibilities of these III-V semiconductors. Our activities include the design and epitaxial growth of complex heterostructures, the device fabrication and characterization.
Resonant tunneling diodes (RTDs) are the fastest semiconductor devices with operation frequencies up to the THz domain. Their active region is typically only a few nanometers wide and their operation utilizes two quantum mechanical effects: tunneling and energy quantization. They can be operated at and above room temperature. RTDs can be used in various applications such as (optically) controlled oscillators, high power GHz oscillators or high-speed photon detectors. We are interested in resonant tunneling diode photodetectors based on the GaAs/AlAs and InAs/GaSb/AlSb material system that allow highly efficient single-photon detection and photon counting for quantum communication applications from the visible to the infrared wavelength range.
We are interested in novel light detectors and emitters for the mid-infrared wavelength region with a focus on the wavelength range between 3 to 7 µm. The mid-infrared wavelength range is especially relevant as molecules and gases have strong absorption lines in this energy range. Via tunable laser-based absorption spectroscopy (TLAS), for example, individual gases and gas mixtures can be probed sensitively and non-destructively. We work on light detectors and emitters that are based on the InAs/GaSb/AlSb material system and use cascaded type-II superlattice structures and carrier selective injector regions to improve the figure of merits, e.g. reduce power consumption, enhance operation temperature and increase detectivities etc.
We are interested in topological insulators based on composite quantum wells of III-V semiconductor materials. Topological insulators based on InAs/Ga(In)Sb have large band gap energies and a rich phase diagram that can be assessed by variations in the quantum well thickness, material composition, strain, electric fields and light. Currently, we are interested in triple quantum wells consisting of InAs/Ga(In)Sb/InAs that allow band gap energies as large as 60 meV in combination with a dual gating access to the full 2D phase diagram.
We are realizing single and entangled photon sources based on semiconductor quantum dots. The quantum dots are grown by our excellent growth team and are usually embedded into nanophotonic cavities for enhanced light extraction. In this context, we are working on highly entangled photon states for quantum computing and quantum communication, frequency conversion of single photons from quantum dots, optimal placement of quantum dots into nanophotonic devices, optimization of nanophotonic devices, fiber coupling of single photons for networking applications, as well as fundamental aspects of light-matter coupling.
As Bachelor and Master thesis we offer sub-topics that are relevant for running projects (within the above-mentioned research scope) and thus this topics change frequently. An example could be “Hyperspectral imaging of quantum dots for placement in nanophotonic cavities” or “Investigation of lifetime-suppression of quantum dots in an optimized planar cavity”.
Master and Bachelor theses can be started at any time, there are always interesting topics available (the two mentioned above are only examples). The first contact is via email. Then, in a personal meeting, we will discuss possible research topics and personal research interests.
Epitaxy provides an exciting possibility to explore the material properties at the nanoscale. At our chair, you will have the opportunity to explore a wide range of III-V material systems for optoelectronic and photonic applications. Quantum dots as 0-dimensional (0-D) structures are excellent single-photon sources, and we work to address all telecom windows for different applications. 2-Dimensional (2-D) structures provide the possibility of stacking materials, and epitaxy is the platform for their realization. Here, we address light-matter interaction in semiconductors and organic-inorganics combinations.
With several MBE machines dedicated for Arsenides, Phosphides, and Antimonides, there are always topics available for Bachelor and Master’s Thesis. The growth-related projects can provide possibilities to work with MBE for growth and with different characterization tools for optimization. For example, some of these tools are Photoluminescence (PL), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), Reflectivity, etc. Few topics are listed below for different material systems:
- Growth and characterization of QDs as single-photon sources
- Growth and characterization of Quantum Wells (QWs)
- Growth and characterization of Resonant tunneling diode structures
There are always more topics available on growth and characterization of QDs, microcavities. Feel free to call and write an email for discussion.