Very high commutation quality factor and dielectric tunability in nanocomposite SrTiO3 thin films with: T c enhanced to >300 °c

Abstract

We report on nanoengineered SrTiO3-Sm2O3 nanocomposite thin films with the highest reported values of commutation quality factor (CQF or K-factor) of >2800 in SrTiO3 at room temperature. The films also had a large tunability of dielectric constant (49%), low tangent loss (tanδ = 0.01) and a Curie temperature for SrTiO3 > 300 °C, making them very attractive for tunable RF applications. The enhanced properties originate from the unique nanostructure in the films, with <20 nm diameter strain-controlling Sm2O3 nanocolumns embedded in a SrTiO3 matrix. Very large out-of-plane strains (up to 2.6%) and high tetragonality (c/a) (up to 1.013) were induced in the SrTiO3. The K-factor was further enhanced by adding 1 at% Sc3+ (acceptor) dopant in SrTiO3 to a value of 3300 with the tangent loss being ≤0.01 up to 1000 kV cm-1.