Division of Spectroscopy
The spectroscopy division concentrates on optical investigations of semiconductors, ion-beam modified semiconductors, and low-dimensional semiconductor heterostructures. The techniques applied are conventional optical characterization methods like FTIR spectroscopy, FTIR microscopy, Raman spectroscopy, luminescence and luminescence excitation spectroscopy, electroluminescence, and infrared near-field microscopy. The main focus of our work is the investigation of dynamic processes on a femtosecond and picosecond time scale. The understanding of these processes is of paramount importance for the development of new materials and ultrafast optoelectronic components.
The present activities focus on the investigation of emitters and detectors for terahertz and mid-infrared radiation, as well as the modification of III-V compounds by nitrogen implantation. Further key topics include the dynamics of charge carriers in quantum well heterostructures, superlattices, quantum dots, and graphene in electric and magnetic fields. Experimental methods include terahertz spectroscopy, nonlinear laser spectroscopy, and time-resolved photoluminescence spectroscopy. Another important activity is the development of III-V nanowires using molecular beam epitaxy.
The time-resolved optical experiments are performed with table-top femtosecond lasers (Ti:sapphire oscillators, amplifiers, OPG/OPA, THz generators) and with the free-electron laser at ELBE. The latter offers unique possibilities for time-resolved spectroscopy in the mid- and far-infrared regimes, in particular for the investigation of semiconductors and their nanostructures. Synchronization of table-top femtosecond lasers to the free-electron laser is also possible (e. g, for two-color experiments). The division is also involved in the application of these measurement techniques at the Dresden High Magnetic Field Laboratory.