Very high commutation quality factor and dielectric tunability in nanocomposite SrTiO3 thin films with Tc 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 (tan δ = 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.