In-plane and polar orientations of ZnO thin films grown on atomically flat sapphire

I. Ohkubo, A. Ohtomo, T. Ohnishi, Y. Mastumoto, H. Koinuma, M. Kawasaki

Research output: Contribution to journalArticlepeer-review

92 Citations (Scopus)

Abstract

Epitaxial ZnO thin films were prepared on atomically flat sapphire (0001) substrates at various temperatures by laser molecular beam epitaxy. On the as-polished substrates, the in-plane orientation of ZnO thin films was found to be ZnO [1010]∥sapphire [1120] regardless of the deposition conditions. However, films on atomically flat substrates showed two in-plane orientations, ZnO [1010]∥sapphire [1010] and ZnO [1010]∥sapphire [1120], rotated by 30° for films grown at low (400-450° C) and high (800-835° C) temperatures respectively. Ion scattering spectroscopy revealed that the former films were (0001) oriented with the Zn-face forming the topmost surface, whereas the latter films had the (0001) orientation with the O-face at the film surface. This orientation change is discussed by taking thermodynamic stability and growth kinetics into account. The films grown at very high temperature (835°C) showed superior crystallinity even in comparison with bulk single crystals.

Original languageEnglish
Pages (from-to)L1043-L1048
JournalSurface Science
Volume443
Issue number1-2
DOIs
Publication statusPublished - 1999 Dec 10
Externally publishedYes

Keywords

  • Diffraction and reflection
  • Ion scattering spectroscopy
  • Single crystal epitaxy
  • X-ray scattering
  • Zinc oxide

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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