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Electronic structure of GaN(0001)‐2 × 2 thin films grown by PAMBE
Author(s) -
Gutt R.,
Lorenz P.,
Tonisch K.,
Himmerlich M.,
Schaefer J. A.,
Krischok S.
Publication year - 2008
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.200802146
Subject(s) - x ray photoelectron spectroscopy , molecular beam epitaxy , reflection high energy electron diffraction , gallium nitride , electron diffraction , materials science , thin film , wide bandgap semiconductor , stoichiometry , band gap , analytical chemistry (journal) , epitaxy , chemistry , diffraction , optoelectronics , nanotechnology , optics , chemical engineering , layer (electronics) , physics , chromatography , engineering
Gallium nitride thin films were grown on silicon carbide (0001) by plasma‐assisted molecular beam epitaxy (PAMBE). The samples were cooled down in nitrogen plasma and characterized in situ by reflection high energy electron diffraction (RHEED), photoelectron spectroscopy (XPS/UPS), and atomic force microscopy (AFM) revealing stoichiometric and smooth GaN films virtually free of contaminations. We present valence band data obtained by UPS with strong emission from surface states inside the fundamental band gap. These states and the observed 2 × 2 surface reconstruction are highly sensitive towards residual molecules. Once these surface states have disappeared the original state could not be recovered by surface preparation methods underlining the necessity of in situ investigations on as‐grown surfaces. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)