Regensburg 2013 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 90: Poster Session: Quantum information systems; Optical properties; Ultrafast phenomena

HL 90.7: Poster

Thursday, March 14, 2013, 16:00–20:00, Poster A

Effects of reduced symmetry on the Raman spectra of Cu_xO_y — •Christian Reindl, Thomas Sander, Christian Heiliger, and Peter J. Klar — I. Physikalisches Institut, Justus-Liebig-Universität Gießen, Heinrich-Buff-Ring 16, 35392 Gießen

Raman spectra of copper oxide make it possible to clearly indentify the three individual phases Cu₂O, Cu₄O₃, and CuO. These assignments are in good aggreement with results of X-ray diffraction measurements performed. Each copper oxide phase possesses a different crystal symmetry leading to typical unique Raman modes. However, in the particular case of Cu₂O, the spectra obtained reveal modes being forbidden in the perfect crystal.

The presented Raman spectra of copper oxide were recorded with a Renishaw InVia Raman microscope using excitation lasers of 325 nm, 532 nm, and 633 nm, respectively. The samples were grown by sputter deposition, CVD, and MBE. Group theory considerations show that reduction of symmetry, originating from vacancies and interstitials within the crystal lattice, leads to a relaxation of selection rules making forbidden modes allowed. This will be discussed with respect to the modes observed.

Furthermore DFT calculations for Raman modes of Cu₂O with various defects such as copper vacancies support this idea.