Infrared dielectric functions and crystal orientation of a-plane ZnO thin films on r-plane sapphire determined by generalized ellipsometry

C. Bundesmann, N. Ashkenov, M. Schubert, A. Rahm, H. V. Wenckstern, E. M. Kaidashev, M. Lorenz, M. Grundmann

Research output: Contribution to journalConference article

33 Scopus citations

Abstract

Generalized infrared spectroscopic ellipsometry for wave numbers from 370 to 1200 cm-1 was applied to study the anisotropic dielectric response of wurtzite-type ZnO thin films grown on r-plane sapphire. Combined wavelength-by-wavelength analysis of data measured at multiple sample in-plane orientations allows for simultaneous extraction of the dielectric function (DF) tensor, the film thickness and the respective ZnO c-axis orientation, specifically in relation to the sapphire substrate. For anisotropic materials and use of generalized ellipsometry, the correlation problem between thickness and DF does not exist. Subsequent line shape analysis of ordinary and extraordinary DFs provides complete A1- and E1-symmetry longitudinal and transverse optical phonon-mode and broadening parameters, together with the static dielectric constants. The epitaxial relations from the ellipsometry data analysis are (1 1 -2 0)ZnO||(0 1 - 1 2) sapphire and [0 0 0 1]ZnO||[0-1 1 1]sapphire, which was confirmed by XRD measurements.

Original languageEnglish (US)
Pages (from-to)161-166
Number of pages6
JournalThin Solid Films
Volume455-456
DOIs
StatePublished - May 1 2004
EventThe 3rd International Conference on Spectroscopic Ellipsometry - Vienna, Austria
Duration: Jul 6 2003Jul 11 2003

Keywords

  • Epitaxial relation
  • Generalized infrared spectroscopic ellipsometry
  • Phonon modes
  • a-Plane ZnO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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