Enhanced dielectric and piezoelectric responses in Zn1-xMgxO thin films near the phase separation boundary

Xiaoyu Kang, Smitha Shetty, Lauren Garten, Jon F. Ihlefeld, Susan Trolier-McKinstry, Jon Paul Maria

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Abstract

Dielectric and piezoelectric properties for Zn1-xMgxO (ZMO) thin films are reported as a function of MgO composition up to and including the phase separation region. Zn1-xMgxO (0.25 ≤ x ≤ 0.5) thin films with c-axis textures were deposited by pulsed laser deposition on platinized sapphire substrates. The films were phase pure wurtzite for MgO concentrations up to 40%; above that limit, a second phase with rocksalt structure evolves with strong {100} texture. With increasing MgO concentration, the out-of-plane (d33,f) and in-plane (e31,f) piezoelectric coefficients increase by 360% and 290%, respectively. The increase in piezoelectric coefficients is accompanied by a 35% increase in relative permittivity. Loss tangent values fall monotonically with increasing MgO concentration, reaching a minimum of 0.001 for x ≥ 0.30, at which point the band gap is reported to be 4 eV. The enhanced piezoelectric response, the large band gap, and the low dielectric loss make Zn1-xMgxO an interesting candidate for thin film piezoelectric devices, and demonstrate that compositional phase transformations provide opportunities for property engineering.

Original languageEnglish (US)
Article number042903
JournalApplied Physics Letters
Volume110
Issue number4
DOIs
StatePublished - Jan 23 2017

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy (miscellaneous)

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