Crystallization of Pb(Zr,Ti)O3 thin films aided by nanosheets seeding: effects on the microstructure and local piezoresponse

The direct integration of functional metal oxide films in flexible devices is a timely topic of the emergent field of flexible electronics. The traditionally high temperatures required for the crystallization of these oxides... [ view full abstract ]

The direct integration of functional metal oxide films in flexible devices is a timely topic of the emergent field of flexible electronics. The traditionally high temperatures required for the crystallization of these oxides are incompatible with the plastic, textile or paper substrates used. Among the different approaches followed to reduce the crystallization temperature [1], the use of seeding layers not only reduces the energy barrier required for the formation of the crystalline phase on their surfaces, but also promotes a heterogeneous nucleation of the oxide crystals, which leads to the formation of preferential crystallographic orientations in the films.

It has been reported that inorganic nanosheets can successfully be used to produce epitaxy on demand, i.e., to prepare perovskite oxide heteroepitaxial films on the amorphous surfaces of Si substrates [2]. But they can also be used for lowering the crystallization temperature of chemical solution deposition (CSD) derived oxide films. In this work we show the effects of the use of a seeding layer of Ca₂Nb₃O₁₀ (CNO) nanosheets on the microstructure, grain size and local piezoelectric properties of the (Pb,Zr)TiO₃ (PZT) films deposited on them. Suspensions of the CNO nanosheets are Langmuir−Blodgett deposited on Pt-coated silicon substrates. Then PZT films are crystallized at temperatures below 500ºC on substrates with and without this seeding layer. From the results of this comparative study of the films by Piezoresponse Force Microscopy we can discuss the suitability of this approach to produce films with enhanced properties at the lowest processing temperatures possible.

1. Bretos et al., Chem. Soc. Rev., 2018, 47, 291.

2. Nijland et al., Adv. Funct. Mater., 2015, 25, 5140.

This work is funded by the Spanish project MAT2016-76851-R and Fundación General CSIC (ComFuturo Programme)