Confirmation of intrinsic electron gap states at nonpolar GaN(1-100) surfaces combining photoelectron and surface optical spectroscopy

The electronic structure of GaN(1–100) surfaces is investigated in-situ by photoelectron spectroscopy (PES) and reflection anisotropy spectroscopy (RAS). Occupied surface states 3.1 eV below the Fermi energy are observed by PES, accompanied by surface optical transitions found in RAS around 3.3 eV,...

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Bibliographic Details
Published in:Applied physics letters 2014-04, Vol.104 (17)
Main Authors: Himmerlich, M., Eisenhardt, A., Shokhovets, S., Krischok, S., Räthel, J., Speiser, E., Neumann, M. D., Navarro-Quezada, A., Esser, N.
Format: Article
Language:English
Subjects:
Anisotropy
Applied physics
CRYSTALS
DENSITY FUNCTIONAL METHOD
Density functional theory
ELECTRONIC STRUCTURE
Energy gap
GALLIUM NITRIDES
MATERIALS SCIENCE
PHOTOELECTRON SPECTROSCOPY
Spectroscopy
Spectrum analysis
SURFACES
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Summary:The electronic structure of GaN(1–100) surfaces is investigated in-situ by photoelectron spectroscopy (PES) and reflection anisotropy spectroscopy (RAS). Occupied surface states 3.1 eV below the Fermi energy are observed by PES, accompanied by surface optical transitions found in RAS around 3.3 eV, i.e., below the bulk band gap. These results indicate that the GaN(1–100) surface band gap is smaller than the bulk one due to the existence of intra-gap states, in agreement with density functional theory calculations. Furthermore, the experiments demonstrate that RAS can be applied for optical surface studies of anisotropic crystals.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4873376