Cation Size Effects on the Electronic and Structural Properties of Solution-Processed In–X–O Thin Films

Jeremy Smith, Li Zeng, Rabi Khanal, Katie Stallings, Antonio Facchetti, Julia E. Medvedeva, Michael J. Bedzyk, Tobin J Marks

Research output: Contribution to journalArticle

22 Citations (Scopus)

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.

Original languageEnglish
Article number1500146
JournalAdvanced Electronic Materials
Volume1
Issue number7
DOIs
Publication statusPublished - 2015

Fingerprint

Electronic properties
Cations
Structural properties
Positive ions
Thin films
Amorphous semiconductors
Temperature
X ray absorption spectroscopy
Electron mobility
Spin coating
Bond length
Thin film transistors
Processing
Indium
Molecular dynamics
Charge transfer
Oxides
Computer simulation
Electric potential

Keywords

  • amorphous oxide semiconductors
  • charge transport
  • local structure simulation
  • thin film transistors
  • X-ray absorption spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

Cite this

Cation Size Effects on the Electronic and Structural Properties of Solution-Processed In–X–O Thin Films. / Smith, Jeremy; Zeng, Li; Khanal, Rabi; Stallings, Katie; Facchetti, Antonio; Medvedeva, Julia E.; Bedzyk, Michael J.; Marks, Tobin J.

In: Advanced Electronic Materials, Vol. 1, No. 7, 1500146, 2015.

Research output: Contribution to journalArticle

Smith, Jeremy ; Zeng, Li ; Khanal, Rabi ; Stallings, Katie ; Facchetti, Antonio ; Medvedeva, Julia E. ; Bedzyk, Michael J. ; Marks, Tobin J. / Cation Size Effects on the Electronic and Structural Properties of Solution-Processed In–X–O Thin Films. In: Advanced Electronic Materials. 2015 ; Vol. 1, No. 7.
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