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Title: Strain-induced optical band gap variation of SnO 2 films

In this paper, thickness dependent strain relaxation effects are utilized to study the impact of crystal anisotropy on the optical band gap of epitaxial SnO 2 films grown by pulsed laser deposition on (0001)-oriented sapphire substrates. An X-ray diffraction analysis reveals that all films are under tensile biaxial in-plane strain and that strain relaxation occurs with increasing thickness. Variable angle spectroscopic ellipsometry shows that the optical band gap of the SnO 2 films continuously increases with increasing film thickness. This increase in the band gap is linearly related to the strain state of the films, which indicates that the main origin of the band gap change is strain relaxation. The experimental observation is in excellent agreement with results from density functional theory for biaxial in-plane strain. Our research demonstrates that strain is an effective way to tune the band gap of SnO 2 films and suggests that strain engineering is an appealing route to tailor the optical properties of oxide semiconductors.
 [1] ;  [2] ;  [2]
  1. Renewable Energies Laboratory, Timisoara (Romania)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Thin Solid Films
Additional Journal Information:
Journal Volume: 615; Journal ID: ISSN 0040-6090
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; Tin oxide; Epitaxial; Pulsed laser deposition; X-ray diffraction; Optical properties; Strain; Bandgap; DFT
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1359950