Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 97: ZnO
HL 97.6: Talk
Friday, March 15, 2013, 11:00–11:15, H16
Raman scattering of H2 in ZnO — •Sandro G. Koch, Edward V. Lavrov, and Jörg Weber — Technische Universität Dresden, 01062 Dresden, Germany
ZnO single crystals thermally treated in a H2, D2, or H2 + D2 ambient at 800–1000 ∘C are studied by Raman scattering. Directly after the treatment most hydrogen forms shallow donors at the bond-centered site. Subsequently, interstitial hydrogen migrates through the lattice and forms electrically inactive H2. The formation process, thermal stability, interaction with the phonon spectrum, position of the molecule in the host lattice, as well as the ortho-para conversion rate are addressed in this study. It is shown that H2 in ZnO is almost a free rotator, which is stable in the temperature range 300–600 ∘C. Arguments are presented that the molecule occupies an interstitial lattice site. It is also shown that at elevated temperatures the para species is absent in Raman spectra, which is explained by thermally activated excitation of the molecule from the J=0 to the J=2 rotational state and phonon broadening of the spectral line associated with J=2.