Piezoelectric coefficients and spontaneous polarization of ScAlN

Miguel Caro, Siyuan Zhang, Tommi Riekkinen, Markku Ylilammi, Michelle A. Moram, Olga Lopez-Acevedo, Jyrki Molarius, Tomi Laurila

Research output: Contribution to journalArticleScientificpeer-review

121 Citations (Scopus)

Abstract

We present a computational study of spontaneous polarization and piezoelectricity in ScxAl1-xN alloys in the compositional range from x = 0 to x = 0.5, obtained in the context of density functional theory and the Berry-phase theory of electric polarization using large periodic supercells. We report composition-dependent values of piezoelectric coefficients eij, piezoelectric moduli dij and elastic constants Cij. The theoretical findings are complemented with experimental measurement of e33 for a series of sputtered ScAlN films carried out with a piezoelectric resonator. The rapid increase with Sc content of the piezoelectric response reported in previous studies is confirmed for the available data. A detailed description of the full methodology required to calculate the piezoelectric properties of ScAlN, with application to other complex alloys, is presented. In particular, we find that the large amount of internal strain present in ScAlN and its intricate relation with electric polarization make configurational sampling and the use of large supercells at different compositions necessary in order to accurately derive the piezoelectric response of the material.

Original languageEnglish
Article number245901
JournalJournal of physics: Condensed matter
Volume27
Issue number24
DOIs
Publication statusPublished - 24 Jun 2015
MoE publication typeA1 Journal article-refereed

Keywords

  • berry phase
  • nitride
  • piezoelectricity
  • polarization
  • ScAlN

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