Prof. Dr. rer. nat. Alexander Holleitner

Courses and Dates

Offered Bachelor’s or Master’s Theses Topics

Optoelectronics of tunnelling devices based on single atomic defects

Structuring materials with atomic precision is the ultimate goal of nanotechnology and is becoming increasingly relevant as an enabling technology for quantum electronics and photonics. The goal of this thesis is to create optically active atomic defects in semiconducting two-dimensional materials, such as MoS2, by helium ion beam lithography with a spatial fidelity approaching the single-atom limit in all three dimensions and to characterize corresponding tunnelling and gate-switching devices. As was demonstrated very recently, such defects can act as single photon emitters with potential applications in quantum communication and sensing. Different layered materials will be combined into few-nm thin heterostructures and they will be integrated into electronic field effect structures to switch the atomic defect states on and off. The material properties will be characterized by different spectroscopies (such as Raman spectroscopy, electron beam and atomic force microscopy). Interest and good knowledge in solid state physics, semiconductor physics, Python programming, optoelectronics or nanofabrication is a plus, but certainly not a must.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Alexander Holleitner

Optoelectronics of two-dimensional topological van der Waals materials

Atomically thin van der Waals crystals form truly two-dimensional materials with remarkable quantum effects. One example is the two-dimensional topological insulator phase, where a two-dimensional sheet of material is insulating, but has conductive one-dimensional edge states. Because of their special topology, these edge states are very robust and can transport both spin and charge, which can find application in quantum information technologies. The goal of this project is to prepare single atomic layers from novel topological materials (such as MoTe2, WTe2 or HfT5) and to study the topological edge conductivity by optoelectronic microscopy. The material properties will be characterized by different spectroscopies (such as atomic force microscopy and Raman spectroscopy). Different layered materials will be combined into few-nm thin heterostructures and they will be integrated into electronic field effect structures to switch the topological states on and off. Interest or good knowledge in solid state physics, semiconductor physics, Python programming, optoelectronics or nanofabrication is a plus, but certainly not a must.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Alexander Holleitner

Symmetries of 2D materials and their heterostacks

Atomically thin van der Waals crystals form truly two-dimensional materials with remarkable quantum effects. Examples range from semi-metallic graphene to topological insulators and semiconducting materials with a thickness of only few atoms. The goal of this project is to characterize the fundamental symmetries of the underlying crystals and optical properties of such two-dimensional materials determined by optical means including Raman, photoluminescence (PL) and second harmonic generation (SHG) measurements, and to understand their optical properties particularly in two-dimensional heterostacks. The latter allow to build atomically thin field-effect, tunnelling, and photovoltaic devices. Interest and good knowledge in solid state physics, semiconductor physics, Python programming, optoelectronics or nanofabrication is a plus, but certainly not a must.

suitable as

• Bachelor’s Thesis Physics

Supervisor: Alexander Holleitner