Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 83: Focus Session: Functionalization of Semiconductors II
HL 83.6: Vortrag
Donnerstag, 10. März 2016, 17:00–17:15, H16
In situ controlled MOVPE-preparation of As-modified Si(100) surfaces and single-domain GaP heteroepitaxy — •Oliver Supplie1,2, Matthias M. May1,2, Agnieszka Paszuk1, Andreas Nägelein1, Peter Kleinschmidt1, Sebastian Brückner1,2, and Thomas Hannappel1,2 — 1TU Ilmenau, Institut für Physik, FG Photovoltaik — 2HZB, Institute Solar Fuels
III-V/Si(100) tandem absorber structures are promising for high-efficiency direct solar watersplitting [1]. MOVPE-processing commonly involves arsenic, either supplied directly via precursors or in form of residuals. Annealing of Si(100) in TBAs and background As results in an As-modified surface with a characteristic reflection anisotropy spectroscopy (RAS) signal. We show that its spectral features emerge at different stages of a two-step annealing process. LEED patterns of the final surface show a preferential A-type, (1× 2) reconstructed surface with dimer rows in parallel to the step edges. These are also clearly visible in STM images. XPS evidences the presence of As at the surface, but also atomic exchange across the interface. Subsequent pseudomorphic GaP heteroepitaxy leads to single-domain GaP/Si(100) surfaces, which are free of antiphase disorder. The sublattice orientation of the GaP film is inverted compared to GaP grown on H-terminated Si [2]. The atomic structure of the heterointerface is more complex than in the abrupt Si-P case [3] for As-free systems.
[1] M. M. May et al., Nat. Commun. 6, 8256 (2015).
[2] O. Supplie et al., Phys. Rev. B 90, 235301 (2014).
[3] O. Supplie et al., J. Phys. Chem. Lett. 6, 464 (2015).