SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 47: Oxide Semiconductors II

HL 47.2: Talk

Friday, March 31, 2023, 09:45–10:00, POT 81

Second harmonic generation of blue series excitons in Cu₂O — •Andreas Farenbruch¹, Dietmar Fröhlich¹, Heinrich Stolz², Dmitri R. Yakovlev^1,3, and Manfred Bayer^1,3 — ¹Experimentelle Physik 2, TU Dortmund, Dortmund, Germany — ²Institut für Physik, Universität Rostock, Rostock, Germany — ³St. Petersburg, Russia

Excitons are Coulomb-bound complexes of electrons and holes in semiconductors with a discrete hydrogen-like energy series. The yellow exciton series in Cu₂O involves excitations between the highest valence and lowest conduction band and it presents an ideal platform for investigations of exciton physics with Rydberg states up to a principal quantum number of n=28. Excitations, that involve the same valence band but the second lowest conduction band belong to the so-called blue series. Access in linear optical spectroscopy to these states is hard to achieve due to the high absorption in this spectral range. Optical second harmonic generation (SHG) is therefore a suitable investigation method. By analyzing the measured polarization dependence of the SHG signal and comparing it with group theoretical simulations, the magneto-Stark and Zeeman effects are identified as the SHG mechanisms involved. The 1S, 2S and 2P excitons and magneto-excitons up to n=8 in magnetic fields up to 10 T are detected. By analyzing their magnetic-field shift and polariton effect, key properties such as the energies of the exciton resonances, the Rydberg energy, the band gap, the reduced exciton mass, the anisotropy of the conduction band mass and the exciton radius are obtained for the blue exciton series.