Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 59: Optical Properties II

HL 59.8: Vortrag

Mittwoch, 9. März 2016, 17:15–17:30, H10

Raman Tensor Formalism for Anisotropic Crystals — •Christian Kranert, Chris Sturm, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Semiconductor Physics Group, Leipzig, Germany

In optically anisotropic materials, the polarization of incident and scattered radiation changes within the crystal along the propagation direction due to birefringence. Consequently, the polarization state at an individual scattering event varies. This prohibits the direct application of the “standard” Raman tensor formalism and causes experimental Raman intensities to generally depend on specifics of the experiment such as focus depth and depth resolution. Therefore it was assumed that the Raman intensities for polarizations, which are not parallel to a principal axis of the dielectric indicatrix, cannot be analytically described. If done anyway, the polarization dependence was modeled using ad-hoc complex phase parameters for the individual Raman tensor elements without connection to a physical property.

We present a modified Raman tensor formalism which allows to model the Raman intensity in dependence on the polarization configuration for any crystal symmetry. It further establishes the complex phase parameters as special case for uniaxial crystals and explains their physical meaning. We explain that for an integration over a sufficiently large depth range, which is fulfilled for bulk samples and typical experimental setups, the depth dependence vanishes. We further discuss the case of an integration over a smaller depth range which is for example required for thin films.