Semiconductor Spectroscopy

Facilities

The facilities for optical spectroscopy include Raman spectroscopy to study the vibrational modes in semiconductor films, heterostructures, and nanowires as well as in topological insulators and graphene. Continuous-wave photoluminescence and photoluminescence excitation spectroscopy from the ultraviolet (244 nm) to the near-infrared spectral region (1.7 μm) are used to investigate III-V films, heterostructures, and nanowires. The spectroscopic techniques for the near-infrared to ultraviolet spectral regions such as Raman and photoluminescence spectroscopy can also be used with a spatial resolution down to about 0.5 μm and in magnetic fields up to 8 T.

 

With cathodoluminescence spectroscopy and imaging in a scanning electron microscope, the spatial resolution can be enhanced into the range of ten nanometers. In addition, element identification is achieved by energy- and wavelength-dispersive x-ray spectroscopy, and the crystallographic orientation as well as the strain state can be determined using electron backscatter diffraction.


Time-resolved photoluminescence spectroscopy on a pico- to microsecond time scale from the ultraviolet (240 nm) to the near-infrared spectral region (1.3 μm) and pump-and-probe spectroscopy with a subpicosecond time resolution are employed to investigate the carrier and polarization dynamics in III-V films, heterostructures, and nanowires.

 

Fourier-transform spectroscopy is used in the far-infrared or terahertz spectral region to record the lasing parameters of quantum-cascade lasers and in the mid-infrared region to study vibrational modes.


The magneto-transport experiments on ferromagnet-semiconductor hybrid devices, semiconductor-based nanoscale systems, and topological insulators can be performed in magnetic fields up to 16 T and at temperatures down to 20 mK.

 

Semiconductor Spectroscopy

Prof. Dr. Holger T. Grahn

Head of Department 

+49 30 20377-318

htgrahn@pdi-berlin.de