Step-flow growth of SrTiO3 thin films with a dielectric constant exceeding 104

The use of SrTiO3 films in cryogenic high-frequency applications has been limited by the low dielectric constant εr of thin films (≈103) when compared to the bulk value of over 104. We show that the extension of the pulsed laser deposition technique to temperatures well above 1000 °C, coupled with in situ reflection high energy electron diffraction monitoring, makes it possible to grow SrTiO3 films in the step-flow mode. Films grown in this mode showed at 4.2 K a maximum εr of 12 700, which could be tuned by 80% by applying a bias voltage of ±1 V.