Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 33: III-V semiconductors II
HL 33.12: Vortrag
Mittwoch, 27. Februar 2008, 17:30–17:45, EW 201
Core levels, valence band structure and unoccupied states of clean InN surfaces — •Marcel Himmerlich, Anja Eisenhardt, Juergen A. Schaefer, and Stefan Krischok — Institut für Physik and Institut für Mikro- und Nanotechnologien, TU Ilmenau, P.O. Box 100565, 98684 Ilmenau, Germany
In this study we used a surface analytics system directly connected to a MBE growth module to study the surface properties of thin InN films. The samples were prepared by plasma assisted molecular beam epitaxy on GaN/Al2O3(0001) templates and exhibited a 2×2 reconstruction after growth. The prepared samples were analysed by photoelectron spectroscopy as well as electron energy loss spectroscopy (EELS). For the occupied states, a very good agreement to available theoretical calculations is found [1,2]. Although, the valence band maximum is located at 1.6 eV, indicating strong downward band bending of ∼ 0.9 eV, photoemission is detected up to EF. This indicates that the Fermi level is pinned above the conduction band minimum, as recently predicted [1]. The spin-orbit splitting of the In4d level at 17.8 eV could be resolved using He II radiation. Furthermore, from the fine structure of the secondary electron cascade peak we extract the energy of different unoccupied states 0 eV to 9 eV above the vacuum level. These measurements enable us to identify features in the InN EELS spectra, with a loss energy larger than 16 eV, as interband transitions from the In4d level.
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