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

Epitaxial c-axis-oriented Bi_3.15Nd_0.85Ti₃O₁₂ (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 ([variant_greek_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/[variant_greek_epsilon]_i ratio are 586 and 1.46 nm, respectively. Knowing the optical dielectric constant ([variant_greek_epsilon]_opt) and the product of [variant_greek_epsilon]_optt_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. [ABSTRACT FROM AUTHOR]