Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 50: Poster II

HL 50.10: Poster

Donnerstag, 30. März 2006, 16:30–19:00, P3

Raman spectroscopy of hydrogen molecules in germanium — •Martin Hiller, Edward Lavrov, and Jörg Weber — Technische Universität Dresden, 01062 Dresden, Germany

Single-crystal germanium wafers exposed to hydrogen and/or deuterium plasmas are studied by means of Raman scattering. The hydrogenation results in H₂ being trapped at different sites within the host lattice. Two bands at 1980 and 4155 cm⁻¹ measured at room temperature are assigned to local vibrational modes of Ge–H and H₂, respectively. Polarization sensitive Raman measurements reveal that the plasma treatment results in the formation of extended planar structures called platelets, similar to the case of hydrogenated silicon. These platelets are aligned predominantly along {111} crystallographic planes and have Ge–H bonds as basic units. The signal at 4155 cm⁻¹ is shown to result from molecular hydrogen trapped within these platelets. Measurements performed at a temperature of 80 K reveal two sharp Raman peaks at 3826 and 3834 cm⁻¹ with an intensity ratio of 3:1, which are assigned to ortho- and para-H₂ trapped at the interstitial T site in germanium. This assignment is supported by the results of recent ab initio calculations. Another signal around 3930 cm⁻¹ seems to be due to H₂ trapped in some other type of voids formed during the plasma treatment. The work was supported by the Deutsche Forschungsgemeinschaft (WE 1319/14).