Interfacial Dead Layers on Lead Free Ferroelectric (K0.5Na0.5)(Mn0.005Nb0.995)O3 Thin Films

Abstract

(K0.5Na0.5)(Mn0.005Nb0.995)O3 (KNMN) thin films of thickness ranging from 200 to 500 nm were deposited on Pt/TiOx/SiO2/Si substrates using a chemical solution deposition. The films exhibit well-established ferroelectric hysteresis loops with a remanent polarization (Pr) of 13–16 µC/cm2. Their coercive voltages exhibit an increase with increasing film thickness, which is accounted for by the existence of an interfacial dead layer. Their dielectric constant demonstrates frequency and thickness dependent behavior, supporting the existence of the interfacial dead layer. We confirmed that interfacial dead layers with thickness di and dielectric constant εi existed in KNMN films using the “in-series capacitor” model. The ratios of dielectric constant and thickness of interfacial dead layers (εi/di) of KNMN thin films were obtained by calculations of 3.84 nm-1 and measurements of 3.75 nm-1, which are in good agreement with the “in-series capacitor” model and experimental results.