Effective thickness and dielectric constant of interfacial layers of Pt/Bi3.15Nd0.85Ti3O12/SrRuO3 capacitors

Abstract

Epitaxial c-axis-oriented Bi3.15Nd0.85Ti3O12 (BNT) thin films with thickness ranging from 150 to 350 nm were deposited on conductive SrRuO3 (SRO) on (001) SrTiO3 substrates by pulsed laser deposition. The top Pt electrode was deposited by sputtering to construct a capacitor Pt/BNT/SRO. The authors have evaluated the effective thickness (t(i)) and dielectric constant (epsilon(i)) of interfacial layers at the Pt/BNT and BNT/SRO interfaces based on the optical refractive index of the BNT layer and the capacitance frequency as well as the current-voltage characteristics of the capacitors. Using a series capacitor model, they have found that the dielectric constant of bulk BNT and the t(i)/epsilon(i) ratio are 586 and 1.46 nm, respectively. Knowing the optical dielectric constant (epsilon(opt)) and the product of epsilon(opt)t(i) of BNT thin films, the authors have estimated that the effective thickness and dielectric constant of the interfacial layers are 20.1 nm and 13.7, respectively. (c) 2007 American Institute of Physics.