Piezoelectric properties of microfabricated (K,Na)NbO3 thin films

A novel microfabrication method of lead-free piezoelectric sodium potassium niobate [(K,Na)NbO3, KNN] thin films was proposed, and the piezoelectric characteristics of the KNN microactuators were evaluated. The KNN thin films were directly deposited on microfabricated Si microcantilevers. The transverse piezoelectric coefficient d31 of the KNN films was calculated as −53.5 pm/V at 20 Vpp from the tip displacement of the microcantilevers. However, the tip displacement showed large electric-field dependence because of the extrinsic piezoelectric effect, and the intrinsic piezoelectric effect of the KNN microcantilevers was smaller than that of KNN on unprocessed thick substrates. In contrast, the extrinsic piezoelectric effect was almost independent of the microfabrication of the KNN films.