Research Assistants

We currently are looking for interested students (Master's theses and doctorate) to participate in our research projects. Contact us for more information!

Epitaxy of indium phosphide heterostructures for innovative THz transistors

Heterostructure bipolar transistors can produce signals at frequencies between 100 and 600 GHz with superior efficiency and linearity. In the context of several projects, we are investigating the further development of THz transistors based on this material system. For this purpose, we use a modern MOCVD facility for atomically exact crystal growth (epitaxy) to generate innovative heterostructures of InP with GaAsSb and graded InGaAs layers. The material analysis is carried out using high-resolution X-ray spectroscopy and TEM imaging. The epitaxed wafers are used to create submicrometer transistors in the clean room of the department in order to experimentally validate the function of the structure.

3D Epitaxy of Gallium Nitride Structures

GaN is still a young semiconductor material, but it is already widely used today: white LEDs and efficient power supplies are only feasible with this material. The hexagonal crystal structure leads to internal polarization fields, which are disadvantageous in some device applications. Epitaxy in the lateral direction on pre-structured templates can avoid the formation of polarization fields. We are developing this epitaxy technology with the aim of realizing high-frequency tunnel diodes with high operating voltage and thus increased output power.

Miniaturized RF Transceivers with Power Transfer

As the frequency increases, antennas become smaller -- the wavelength determines their extent. At 300 GHz, λ/2 is only half a millimeter. Together with micrometer-sized components, miniaturized sensors with RF data transmission can be realized at these frequencies. This opens up the use of smart sensors in spatially restricted environments. A central problem is the energy supply of autonomous microsensors. This is done here via the terahertz wave by means of energy harvesting. In several projects, we are investigating the realization of THz resonance tunneling diodes based on indium phosphide heterostructures, which are epitaxed with our MOCVD system. The diodes with monolithically integrated antennas are produced in the clean room using electron beam lithography and other chip technologies, and then validated in the measurement laboratory at THz frequencies.