Enhanced Electron Mobility Due to Dopant-Defect Pairing in Conductive ZnMgO

Yi Ke, Stephan Lany, Joseph J. Berry, John D. Perkins, Philip A. Parilla, Andriy Zakutayev, Tim Ohno, Ryan O'Hayre, David S. Ginley

Research output: Contribution to journalArticlepeer-review

50 Scopus Citations

Abstract

The increase of the band gap in Zn1-xMgxO alloys with added Mg facilitates tunable control of the conduction band alignment and the Fermi-level position in oxide-heterostructures. However, the maximal conductivity achievable by doping decreases considerably at higher Mg compositions, which limits practical application as a wide-gap transparent conductive oxide. In this work, first-principles calculations and material synthesis and characterization are combined to show that the leading cause of the conductivity decrease is the increased formation of acceptor-like compensating intrinsic defects, such as zinc vacancies (VZn), which reduce the free electron concentration and decrease the mobility through ionized impurity scattering. Following the expectation that non-equilibrium deposition techniques should create a more random distribution of oppositely charged dopants and defects compared to the thermodynamic limit, the paring between dopant GaZn and intrinsic defects VZn is studied as a means to reduce the ionized impurity scattering. Indeed, the post-deposition annealing of Ga-doped Zn0.7Mg0.3O films grown by pulsed laser deposition increases the mobility by 50% resulting in a conductivity as high as σ = 475 S cm-1.

Original languageAmerican English
Pages (from-to)2875-2882
Number of pages8
JournalAdvanced Functional Materials
Volume24
Issue number19
DOIs
StatePublished - 2014

NREL Publication Number

  • NREL/JA-5F00-62248

Keywords

  • band-gap engineering
  • defect-pairing
  • ionized impurity scattering
  • non-equilibrium thin film
  • transparent conducting oxides

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