High angle annular dark field and electron energy loss spectroscopy study on the substitution and distribution of cobalt in ZnO by multilayer growth

Shu Fang Chen, Chuan Pu Liu, H. S. Hsu, J. C.A. Huang

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3 Citations (Scopus)

Abstract

Co-doped ZnO films were synthesized by ion beam sputtering using multilayer (ZnO/Co) growth. Both the distribution and the chemical states of Co in ZnO can be well controlled by varying the ratio of the nominal layer thickness of ZnO to Co. Transmission electron microscopy indicated that all of the as-deposited Zn1-x (Co) x O films were polycrystalline with a (0002) preferred orientation. The local microstructures and chemical states were identified by Z -contrast imaging and electron energy loss spectroscopy. In ZnO (1.5 nm)/Co (0.1 nm), homogeneous Co-doped ZnO was observed to have been formed through interdiffusion. However, decreasing or increasing the thickness of ZnO leads to the formation of Co clusters in the ZnO matrix or Zn1-x (Co) x O multilayers, respectively. For ZnO thickness1.5 nm, Co is substituted for Zn, and its valence state is 2+. All Co-doped ZnO films show roomerature ferromagnetic behavior, which appears to depend strongly on the Co distribution.

Original languageEnglish
Article number083507
JournalJournal of Applied Physics
Volume104
Issue number8
DOIs
Publication statusPublished - 2008 Nov 7

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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