Effects of non-stoichiometry on the microstructure, oxygen vacancies, and electrical properties of KNN-based thin films

Chung Ming Weng, Cheng Che Tsai, Cheng Shong Hong, Chun Cheng Lin, Chan Ching Chen, Sheng Yuan Chu, Jyh Sheen, Zong You Chen, Hsiu Hsien Su

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Highly piezoelectric lead-free thin films of (K0.5Na0.5)NbO3 + x mol% Na(I) and K(I) (KNN, x = 0-50 mol%) were fabricated using a sol-gel method on Pt (111)/Ti/SiO2/Si(100) substrates and the effects of additives on microstructure, oxygen vacancies, and electrical properties of the proposed samples were investigated. Excess quantities of Na(I) and K(I) were shown to decrease the formation of secondary phases and promote the effective growing of the grains. The addition of these elements was also shown to inhibit the formation of alkaline ion vacancies and decrease the leakage current density. Our findings indicate that the crystallinity and microstructure of the samples have a stronger effect than the oxygen vacancies on the piezoelectric properties of KNN films. Non-stoichiometric KNN films showed the highest remnant polarization (Pr = 11.2 μC/cm2), piezoelectric coefficient (d33 = 40.23 pm/V), voltage coefficient (g33 = 7.9 mm V/N), and lowest leakage current (∼3.46 × 10-7 A/cm2) when the excess ratio was 40 mol% following annealing at 700°C. Our results also demonstrate that the transport mechanism of the films is governed by Ohmic behavior under low electric fields and the effects of Poole-Frenkel emission under a strong electric field.

Original languageEnglish
Pages (from-to)N49-N56
JournalECS Journal of Solid State Science and Technology
Volume5
Issue number9
DOIs
Publication statusPublished - 2016 Jan 1

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials

Fingerprint Dive into the research topics of 'Effects of non-stoichiometry on the microstructure, oxygen vacancies, and electrical properties of KNN-based thin films'. Together they form a unique fingerprint.

  • Cite this