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Article
Cation Size Effects on the Electronic and Structural Properties of Solution-Processed In-X-O Thin Films
Advanced Electronic Materials
  • Jeremy Smith
  • Li Zeng
  • Rabi Khanal
  • Katie Stallings
  • Antonio Facchetti
  • Julia E. Medvedeva, Missouri University of Science and Technology
  • Michael J. Bedzyk
  • Tobin J. Marks
Abstract
The nature of charge transport and local structure are investigated in amorphous indium oxide-based thin films fabricated by spin-coating. The In-X-O series where X = Sc, Y, or La is investigated to understand the effects of varying both the X cation ionic radius (0.89-1.17 Å) and the film processing temperature (250-300 °C). Larger cations in particular are found to be very effective amorphosizers and enable the study of high mobility (up to 9.7 cm2 V-1 s-1) amorphous oxide semiconductors without complex processing. Electron mobilities as a function of temperature and gate voltage are measured in thin-film transistors, while X-ray absorption spectroscopy and ab initio molecular dynamics simulations are used to probe local atomic structure. It is found that trap-limited conduction and percolation-type conduction mechanisms convincingly model transport for low- and high-temperature processed films, respectively. Increased cation size leads to increased broadening of the tail states (10-23 meV) and increased percolation barrier heights (24-55 meV) in the two cases. For the first time in the amorphous In-X-O system, such effects can be explained by local structural changes in the films, including decreased In-O and In-M (M = In, X) coordination numbers, increased bond length disorder, and changes in the MO x polyhedra interconnectivity.
Department(s)
Physics
Research Center/Lab(s)
Center for High Performance Computing Research
Keywords and Phrases
  • Amorphous Oxide Semiconductors,
  • Charge Transport,
  • Local Structure Simulation,
  • Thin Film Transistors,
  • X-Ray Absorption Spectroscopy
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2015 Blackwell Publishing Ltd, All rights reserved.
Publication Date
7-1-2015
Citation Information
Jeremy Smith, Li Zeng, Rabi Khanal, Katie Stallings, et al.. "Cation Size Effects on the Electronic and Structural Properties of Solution-Processed In-X-O Thin Films" Advanced Electronic Materials Vol. 1 Iss. 7 (2015) ISSN: 2199-160X
Available at: http://works.bepress.com/julia-medvedeva/37/