PL spectroscopy laboratory
The spectroscopy laboratory is used for photoluminescence (PL), PL excitation (PLE), photocurrent (PC), and photoreflectance (PR) spectroscopy covering a wide spectral range for materials investigated in the institute. The samples mounted in a He-flow cryostat can be investigated at temperatures between 4 and 500 K. The experiments range from routine characterization of semiconductor heterostructures to studies of the electric-field dependent population of subbands in quantum-cascade structures for which a high level of stray-light rejection is required. Tunable excitation sources allow for the investigation of energy-dependent carrier transport.
Specifications of the PL spectroscopy laboratory
PL spectra of an undoped MIR quantum-cascade structure:
Grey-scale presentation of normalized, electric-field-dependent PL spectra showing the conduction band ground state and the lower laser level below as well as above a critical field strength for (a) excitation at 1.55 eV and (b) at 1.70 eV, i.e. the anti-Stokes and the Stokes configuration, respectively. For comparison, the calculated transition energies are indicated.

