Growth of {100}-oriented lead zirconate titanate thin films mediated by a safe solvent

Abstract

Chemical solution deposition (CSD) is a well-established process for the fabrication of metal oxide functional layers such as piezoelectric lead zirconate titanate (PZT) thin films. The latter exhibit an enhanced electromechanical response in the presence of {100} crystalline orientation with respect to the substrate surface. Lead titanate (PbTiO₃) seed layers are commonly used to promote the growth of this orientation on platinized silicon, which otherwise usually affords the {111} orientation. In this work, we present a comparative study of two solvents used for the preparation of PZT and PbTiO₃ solutions for CSD, i.e. the popular but highly carcinogenic and teratogenic solvent 2-methoxyethanol and the benign solvent 1-methoxy-2-propanol. In addition to tremendous health and safety benefits, we show that 1-methoxy-2-propanol-derived PbTiO₃ seed layers promote the {100} orientation more efficiently than their 2-methoxyethanol-derived counterparts, owing to their nanocrystalline microstructure and strong orientation. This resulted in a noticeable enhancement of the electrical and piezoelectric properties, with P_r = 38 μC cm⁻², E_c = 55 kV cm⁻¹, ε_r = 1300, tan δ = 0.04 and e_31,f ≈ 14 C m⁻².