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This content will become publicly available on February 2, 2017

Title: Continuously controlled optical band gap in oxide semiconductor thin films

The optical band gap of the prototypical semiconducting oxide SnO2 is shown to be continuously controlled through single axis lattice expansion of nanometric films induced by low-energy helium implantation. While traditional epitaxy-induced strain results in Poisson driven multidirectional lattice changes shown to only allow discrete increases in bandgap, we find that a downward shift in the band gap can be linearly dictated as a function of out-of-plane lattice expansion. Our experimental observations closely match density functional theory that demonstrates that uniaxial strain provides a fundamentally different effect on the band structure than traditional epitaxy-induced multiaxes strain effects. In conclusion, charge density calculations further support these findings and provide evidence that uniaxial strain can be used to drive orbital hybridization inaccessible with traditional strain engineering techniques.
Authors:
 [1] ;  [2] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Photovoltaics, National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara (Romania)
Publication Date:
OSTI Identifier:
1245355
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 16; Journal Issue: 3; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY strain doping; tin oxide; helium ion implantation; ellipsometry; uniaxial strain