Artificially induced normal ferroelectric behaviour in aerosol deposited relaxor 65PMN–35PT thick films by interface engineering

Abstract

A thin dielectric layer of Al₂O₃ was grown by atomic layer deposition on a relaxor ferroelectric 65Pb(Mg_1/3Nb_2/3)O₃–35PbTiO₃ (PMN–PT)/Pt/Si thick film fabricated by the aerosol deposition technique to artificially induce ferroelectric behaviour. The frequency and temperature-dependent dielectric properties with a reduced degree of diffuseness (γ, from 1.9 to 1.5) and the change in the shape of the polarization–electric field curves (from slim relaxor with low hysteresis to square type ferroelectric with high hysteresis) confirm the modulation of its pristine relaxor ferroelectric nature with a change in the Al₂O₃ layer thickness. An increase in the maximum dielectric temperature (T_m), remnant polarisation (P_r), coercive field (E_c), and impedance was observed with increasing thickness of the Al₂O₃ dielectric layer, which can be attributed to the accumulation of charge carriers at the interface of the Pt/Al₂O₃/PMN–PT/Pt/Si heterostructure in the presence of an external electric field. Leakage characteristics also support the artificially induced ferroelectric behaviour in the Pt/Al₂O₃/PMN–PT/Pt/Si heterostructure. The aftereffects of the dielectric Al₂O₃ interface layer over the relaxor ferroelectric film is discussed in detail.