Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 92: Poster Session: II-VI Semiconductors & ZnO and related Materials

HL 92.14: Poster

Thursday, March 29, 2012, 16:00–19:00, Poster D

Polarisation dependence of UV Raman scattering in ZnO — •Christian Kranert, Rüdiger Schmidt-Grund, and Marius Grundmann — Universität Leipzig, Institut für Experimentelle Physik II, Semiconductor Physics Group, Leipzig, Germany

The usage of UV lasers for the excitation of Raman scattering in wide-bandgap semiconductors has become popular in recent times. This is mainly due to the fact that their light is strongly absorbed in the material allowing for a higher depth (and lateral) resolution which is particularly attractive for micro- and nanosized samples. However, there is a lack of basic research in this field which we show to be essential for a correct interpretation of the acquired spectra.

We present polarisation dependent Raman scattering spectra of bulk ZnO excited by the 325 nm line of a HeCd laser. These are dominated by peaks attributed to "forbidden" (=Fröhlich interaction induced, exciton mediated) scattering from longitudinal optical (LO) phonons. In contradiction to commonly made assumptions, the spectral position as well as lineshape and relative intensity of these peaks show a clear dependence on the applied polarisation configuration, i.e. polarisation of the scattered light relative to the incident light and polarisation of the incident light relative to the c-axis, respectively. A discussion on the observed effects will be given.