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Analysis of polar GaN surfaces with photoelectron and high resolution electron energy loss spectroscopy
Author(s) -
Lorenz Pierre,
Haensel Thomas,
Gutt Richard,
Koch Roland J.,
Schaefer Juergen A.,
Krischok Stefan
Publication year - 2010
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200983691
Subject(s) - x ray photoelectron spectroscopy , reflection high energy electron diffraction , band bending , high resolution electron energy loss spectroscopy , molecular beam epitaxy , photoemission spectroscopy , materials science , electron diffraction , spectroscopy , full width at half maximum , ultraviolet photoelectron spectroscopy , chemistry , atomic physics , analytical chemistry (journal) , electron energy loss spectroscopy , epitaxy , diffraction , optics , physics , transmission electron microscopy , nuclear magnetic resonance , optoelectronics , nanotechnology , layer (electronics) , quantum mechanics , chromatography
Abstract The properties of Ga‐face and N‐face GaN surfaces were studied by X‐ray and ultraviolet photoelectron spectroscopy (XPS, UPS), atomic force microscopy (AFM), reflection high energy electron diffraction (RHEED) as well as high resolution electron energy loss spectroscopy (HREELS). The Ga‐face GaN was grown on 6H‐SiC(0001) and the N‐face GaN directly on α‐Al 2 O 3 (0001) by plasma assisted molecular beam epitaxy (PAMBE) and in situ analysed by photoelectron spectroscopy. The Ga‐face GaN surfaces show a 2 × 2 reconstruction measured by RHEED. From the analysis of the XPS spectra a valence band maximum located 2.9 eV below the Fermi level results. Furthermore, the UPS spectra exhibit two surface states. The N‐face GaN presented a 1 × 1 surface with one surface state and a valence band maximum located 2.4 eV below E F . These values correspond to an upward band bending of about 0.9 eV for the N‐face GaN( $000\bar {1}$ )‐1 × 1 and about 0.4 eV for the GaN(0001)‐2 × 2 (Ga‐face) results. The different surface band bending is further supported by the evaluation of the FWHM of the quasi‐elastically reflected electrons in HREELS.