Structural and physical property studies of amorphous Zn-In-Sn-O thin films

Diana E. Proffit, Qing Ma, Donald B. Buchholz, Robert P.H. Chang, Michael J. Bedzyk, Thomas O. Mason

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Abstract

The structures in amorphous (a-) Zn, Sn co-doped In 2O 3 (ZITO) thin films grown by pulsed laser deposition on glass under varying oxygen pressure or with varying Sn:Zn ratios were determined using X-ray absorption spectroscopy and anomalous X-ray scattering. Typical structures around cations in a-ZITO films are described and compared with crystalline (c-) ZITO films. The results show that the Zn cations are fourfold coordinated with Zn-O bond lengths of 1.98 ± 0.02 Å which is close to that in bulk ZnO. As a consequence, the second coordination shells around Zn contract. At longer distances away from Zn, the structure is commensurate with the averaged structure. The unit volume around In also contracts slightly compared to bulk In 2O 3, whereas the Sn-O bond length is similar to the one in bulk SnO 2. These unique structural characteristics may account for the films' superior thermal stability over amorphous Sn-doped In 2O 3, and suggest that Zn and Sn act as network-forming cations. Like in c-ZITO, coordination numbers (N) around Sn, In, and Zn follow the order N Sn > N In > N Zn. Unlike in c-ZITO, where electrical properties change significantly with a slight variation in the Sn:Zn ratio, this variation does not markedly alter the electrical properties, or the local structures, of a-ZITO films. Dramatic changes in the electrical properties occur for films grown under various oxygen pressures, which point to oxygen "defects" as the source of charge carriers.

Original languageEnglish
Pages (from-to)3657-3664
Number of pages8
JournalJournal of the American Ceramic Society
Volume95
Issue number11
DOIs
Publication statusPublished - Nov 1 2012

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ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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