Correlation of interfacial and dielectric characteristics in atomic layer deposited Al₂O₃/TiO₂ nanolaminates grown with different precursor purge times

Considering the potential applications of Al₂O₃/TiO₂ nanolaminates (ATA NLs) in storage capacitors, device-grade ATA NLs are fabricated using an ALD system, wherein the effect of precursor purging time on interfacial, and dielectric properties is thoroughly investigated. With an increase in half-cycle purging time from 2 to 4 s, the observed improvement in interface quality and sublayer density of these NLs is ascribed to the efficient removal of reaction by-products and impurities. Moreover, with an increase in purge time from 2 to 4 s, the increase in dielectric constant and concurrent decrease in dielectric loss from ∼132 to 154 and from ∼0.29 to 0.2, respectively, are primarily assigned to the improvement in sublayer conductivity contrast assisted Maxwell–Wagner interfacial polarization across Al₂O₃/TiO₂ interfaces. The NL based devices fabricated at 4 s purging time, exhibited a capacitance density of ∼18.94 fF/μm², low equivalent oxide thickness of ∼1.82 nm, and reduced leakage current density of ∼3.04 × 10⁻⁵ A/cm² at 2 V applied bias, which demonstrates its suitability as high-k materials for energy storage applications. Furthermore, this study not only gives an insight of the purging time induced growth chemistry of ATA NLs but also explores the possibility of improving its dielectric performance essential for multifaceted applications.