Thermal Conductivity Comparison of Indium Gallium Zinc Oxide Thin Films: Dependence on Temperature, Crystallinity, and Porosity

Boya Cui, Li Zeng, Denis Keane, Michael J. Bedzyk, D. Bruce Buchholz, Robert P. H. Chang, Xinge Yu, Jeremy Smith, Tobin J Marks, Yu Xia, Antonio F. Facchetti, Julia E. Medvedeva, M. Grayson

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The cross-plane thermal conductivity of InGaZnO (IGZO) thin films was measured using the 3ω technique from 18 to 300 K. The studied morphologies include amorphous (a-IGZO), semicrystalline (semi-c-IGZO), and c-axis-aligned single-crystal-like IGZO (c-IGZO) grown by pulsed laser deposition (PLD) as well as a-IGZO deposited by sputtering and by solution combustion processing. The atomic structures of the amorphous and crystalline films were simulated with ab initio molecular dynamics. The film quality and texturing information was assessed by X-ray diffraction and grazing incidence wide-angle X-ray scattering. X-ray reflectivity was also conducted to quantify film densities and porosities. All the high-density films exhibit an empirical power-law temperature dependence of the thermal conductivity κ ∼ T0.6 in the specified temperature range. Among the PLD dense films, semi-c-IGZO exhibits the highest thermal conductivity, remarkably exceeding both films with more order (c-IGZO) and with less order (a-IGZO) by a factor of 4. The less dense combustion-synthesized films, on the other hand, exhibited lower thermal conductivity, quantitatively consistent with a porous film using either an effective medium or percolation model. All samples are consistent with the porosity-adapted Cahill-Pohl (p-CP) model of minimum thermal conductivity.

Original languageEnglish
Pages (from-to)7467-7475
Number of pages9
JournalJournal of Physical Chemistry C
Volume120
Issue number14
DOIs
Publication statusPublished - Apr 21 2016

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

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    Cui, B., Zeng, L., Keane, D., Bedzyk, M. J., Buchholz, D. B., Chang, R. P. H., Yu, X., Smith, J., Marks, T. J., Xia, Y., Facchetti, A. F., Medvedeva, J. E., & Grayson, M. (2016). Thermal Conductivity Comparison of Indium Gallium Zinc Oxide Thin Films: Dependence on Temperature, Crystallinity, and Porosity. Journal of Physical Chemistry C, 120(14), 7467-7475. https://doi.org/10.1021/acs.jpcc.5b12105