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Title: Electronic structure of Al- and Ga-doped ZnO films studied by hard X-ray photoelectron spectroscopy

Al- and Ga-doped sputtered ZnO films (AZO, GZO) are semiconducting and metallic, respectively, despite the same electronic valence structure of the dopants. Using hard X-ray photoelectron spectroscopy we observe that both dopants induce a band in the electronic structure near the Fermi level, accompanied by a narrowing of the Zn 3d/O 2p gap in the valence band and, in the case of GZO, a substantial shift in the Zn 3d. Ga occupies substitutional sites, whereas Al dopants are in both substitutional and interstitial sites. The latter could induce O and Zn defects, which act as acceptors explaining the semiconducting character of AZO and the lack of variation in the optical gap. By contrast, mainly substitutional doping is consistent with the metallic-like behavior of GZO.
Authors:
;  [1] ;  [2] ;  [3] ;  [4]
  1. Lab. de Materiales and Superficies, Dpto. de Física Aplicada I, Universidad de Málaga, 29071 Málaga (Spain)
  2. Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, I-34149 Trieste (Italy)
  3. CEA, DSM/IRAMIS/SPCSI, F-91191 Gif-sur-Yvette Cedex (France)
  4. Synchrotron SOLEIL, BP 48, 91192 Gif-sur-Yvette, France and Institut des NanoSciences de Paris, UPMC Paris 06, CNRS UMR 7588, 4 Place Jussieu, 75005 Paris (France)
Publication Date:
OSTI Identifier:
22269564
Resource Type:
Journal Article
Resource Relation:
Journal Name: APL Materials; Journal Volume: 2; Journal Issue: 1; Other Information: (c) 2014 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; DEFECTS; DOPED MATERIALS; ELECTRONIC STRUCTURE; FERMI LEVEL; FILMS; HARD X RADIATION; PHOTOELECTRON SPECTROSCOPY; SPUTTERING; ZINC OXIDES