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

The use of ${\mathrm{SrTiO}}_{\mathrm{3}}$ films in cryogenic high-frequency applications has been limited by the low dielectric constant ${\epsilon }_r$ of thin films ${\text{(≈10}}^3)$ when compared to the bulk value of over ${10}^4.$ We show that the extension of the pulsed laser deposition technique to temperatures well above $\text{1000\hspace{0.05em}°}\mathrm{C},$ coupled with in situ reflection high energy electron diffraction monitoring, makes it possible to grow ${\mathrm{SrTiO}}_{\mathrm{3}}$ films in the step-flow mode. Films grown in this mode showed at 4.2 K a maximum ${\epsilon }_r$ of 12 700, which could be tuned by 80% by applying a bias voltage of $\text{±1\hspace{0.05em}}\mathrm{V}.$