Improving the structural quality and electrical resistance of SrTiO₃ thin films on Si (001) via a two-step anneal

We report on the optimization of structural and electrical properties of SrTiO₃ thin films grown on Si (001) by hybrid molecular beam epitaxy. Using a dual buffer layer template, 46-nm-thick films grown at high temperatures (850 °C) resulted in a layer-by-layer growth mode and a good crystalline quality with rocking curve full width at half maximum (FWHM) of the 002 SrTiO₃ peak of nearly 0.6°, which was reduced to 0.4° by increasing the film thickness to 120 nm. A high temperature post-deposition anneal was employed to further reduce the rocking curve FWHM down to 0.2° while preserving a smooth film surface morphology. The low sheet resistance of as-grown and post-growth annealed samples was increased by five orders of magnitude exceeding 10⁷ Ω/◻ using a lower temperature anneal in dry air. This two-step annealing method provides an easy and effective way to improve the crystalline quality of SrTiO₃ thin films on Si, providing a path towards the development of electrically insulating, wafer scale virtual perovskite substrates