Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 12: Poster I

HL 12.17: Poster

Montag, 8. März 2004, 16:30–19:00, Poster A

MIR Fourier transformation spectroscopy on Cu₂O — •M. Jörger, K.C. Agarwal, T. Fleck, and C. Klingshirn — Institut für Angewandte Physik, Universität Karlsruhe, D-76128 Karlsruhe

While the far infrared (FIR) optical properties of the direct semiconductor Cu₂O are well understood and dominated by the fundamental phonon modes, the situation in the mid infrared (MIR) is quite different.

Based on the absorption data of a series of naturally grown samples from different sources, with different thicknesses and orientations, we discuss miscellaneous absorption bands in the range of 100-400meV, which partly show a pronounced temperature dependence. It will be analysed to what extent the occurring bands can be explained in terms of biphonon or multiphonon states, intrinsic impurities or, at higher temperatures, in terms of excitonic/electronic transitions.

Depending on the combination of the involved valence and conduction band, there are four different exciton series in Cu₂O. Those are (with increasing band gap) the yellow, green, blue and violet ones. In a so-called pump and probe experiment (cw excitation) we investigate whether 1s(ortho/para)→2p,3p,... transitions within the yellow series can be observed. Furthermore we examine if transitions from the yellow 1s (ortho/para) exciton to states of the higher exciton series appear.