Lead-free piezoelectric thin films for RoHS devices

This paper reports a study of Ba0.9Sr0.1TiO3 and BaTi0.98Sn0.02O3 thin films elaborated by a sol-gel route and deposited on Pt/Ti/SiO2/Si substrates. These films were annealed at 950 degrees C and exhibited a polycrystalline structure. The AFM analysis revealed an important difference in the microstructure of the BST and BTS films. Our BTS film showed no significant piezoelectric properties as its coefficients were d(33) = 5 pC/N and 4 pm/V for the direct and reverse measurements. Under our optimized annealing conditions, we gave the evidence that ferroelectric Ba0.9Sr0.1TiO3 could be a good candidate to replace PZT in RoHS microelectronic devices, therefore for green applications where lead must be prohibited, and that, despite the factor 2 or 3 between coefficients measured on PZT and lead-free films. (C) 2015 Elsevier B.V. All rights reserved.