The group of Optoelectronic Materials and Devices at the University of Paderborn focuses its research on the fabrication and characterization of semiconductor heterostructures for optical and electronic applications, for instance in quantum-information technology.
In these semiconductor heterostructures quantum effects are employed in order to realize new properties. Atomically sharp energy levels in semiconductor quantum dots are one example.
One major focus of our work is the fabrication of semiconductor heterostructures by molecular beam epitaxy (MBE), an ultra-high-vacuum deposition process that allows highest material quality as well as highest material purity. After growth, these heterostructures are analyzed structurally, optically and electrically. For structural examination high-resolution x-ray diffraction, scanning and transmission electron microscopy as well as atomic force microscopy is used.The samples are optically characterized by photoluminescence spectroscopy and reflectivity measurements. The experiments can be performed at room temperature as well as at low temperatures.
For electrical characterization mainly Hall-effect measurements, capacitance voltage spectroscopy and current-voltage measurements are employed. Seminconductor heterostructures are partly further processed into basic devices whereby modern patterning processes, for example electron beam lithography and reactive ion etching (RIE), are used. A special feature of the work group are the different semiconductor material systems, which cover the wide spectral range from infrared to ultraviolet light.
In detail, we produce heterostructures on the basis of the following semiconductor systems: