The work group Callsen at the Institute of Solid State Physics analyzes the optical properties of semiconductors and semiconductor hybrid nanostructures. This includes quantum wells, wires, and dots, which can be employed in single photon sources, LEDs and semiconductor lasers. Along other methods, microphotolumiescence spectroscopy is mainly used for the optical characterization. For these experiments, light sources of different wavelengths in the visible and near-UV spectral region are available. Time-resolved measurements can be performed using a Titanium-Saphire-Laser with frequency doubling, allowing for the analysis of dynamic processes in materials on a scale of femto- to nanoseconds.
A further point of emphasis of the working group is the thermal characterization of nanostructured semiconductors. For this one- and two-beam raman techniques are used; along with time- and frequency-domain thermal reflectance measurements.