Influence of PbO content on the dielectric failure of Nb‐doped {100}‐oriented lead zirconate titanate films

Abstract

Abstract A series of niobium‐doped, {100} textured, “gradient free,” lead zirconate titanate ( PNZT ) films with different PbO contents were fabricated by the chemical solution deposition method. The films’ PbO content was controlled by changing the average PbO content in the solution from 114.7 to 117 at.%. During the dielectric breakdown process of 1.5 μm thick PNZT films with Pt top and bottom electrodes, two phenomena were observed: cracking and thermal breakdown of the piezoelectric film. At 150°C, with an applied 400 kV/cm electric field, the crack density of PNZT films induced by electromechanical failure increased from 0.060/μm to 0.090/μm as the solution's PbO content increased from 114.7% to 117%. In addition, the films showed higher crack densities and more frequent thermal breakdown events when the electric field was oriented downward (from top to bottom electrode) compared with an upward oriented electric field (from bottom to top electrode). The films with higher PbO content had a lower breakdown strength. Also, all films showed lower breakdown strength when measured in the field down direction. The Schottky barrier height ( SBH ) decreased from 0.82 ± 0.06 to 0.68 ± 0.04 eV in the field up direction measurement as the PbO content increased. The SBH value did not show significant change in the field down direction measurement. This suggests that the asymmetry in the film/electrode interfaces is a function of the PbO content in the original solution.