Lead-free Mn-doped (K0.5,Na0.5)NbO3 piezoelectric thin films for MEMS-based vibrational energy harvester applications

• Published in: Applied physics letters 2016-06, Vol.108 (23)
• Main Authors: Won, Sung Sik, Lee, Joonhee, Venugopal, Vineeth, Kim, Dong-Joo, Lee, Jinkee, Kim, Ill Won, Kingon, Angus I., Kim, Seung-Hyun
• Format: Article
• Language: English
• Subjects: Applied physics; Current density; Energy harvesting; Lead free; Leakage current; Maximum power; Microelectromechanical systems; Niobates; Organic chemistry; Piezoelectricity; Thin films
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4953623

Lead-free Mn-doped (K0.5, Na0.5)NbO3 (KNN) thin films were fabricated by the chemical solution deposition method. The addition of small concentration of Mn dopant effectively reduced the leakage current density and enhanced the piezoelectric properties of the films. The leakage current density of 0.5 mol. % Mn-doped KNN film showed the lowest value of ∼10-7 A/cm2 at 10 V compared to the films with other doping concentrations and the piezoelectric d33 and e31 coefficients of this film were ∼90 pm/V and −8.5 C/m2, respectively. The maximum power and power density of the lead-free thin film-based vibrational energy harvesting device were 3.62 μW and 1800 μW/cm3 at the resonance frequency of 132 Hz and the acceleration of 1.0 G. The results prove that the 0.5 mol. % Mn-doped KNN film is an attractive candidate transducer layer for the piezoelectric MEMS energy harvesting device applications with a small volume and a long-lasting power source.