Thickness dependence of the nanoscale piezoelectric properties measured by piezoresponse force microscopy on (1 1 1)-oriented PLZT 10/40/60 thin films

(1 1 1)-oriented Pb0.85La0.1Zr0.4Ti0.6O3 (PLZT 10/40/60) thin films with thickness of 50 nm, 135 nm, 270 nm, 380 nm and 650 nm have been grown on TiOx/Pt(1 1 1)/TiO2/SiO2/Si substrates. Surface morphology, ferroelectric domain architecture, switching properties and piezoelectric activity have been investigated by atomic force microscopy (AFM), piezoresponse force microscopy (PFM) and local piezoelectric hysteresis loops. No significant thickness dependence of the architecture of the ferroelectric domains is evidenced. A progressive shift towards positive voltages is observed on the local loops. The coercive voltage increases with the thickness of the film, as measured on the phase loops. The progressive building of space charges at the interfaces is proposed to explain these evolutions. On the other hand, the local piezoelectric activity, measured from amplitude loops with AFM setup, is shown to be similar for all the films in the 50–650 nm range of thickness.