A low-temperature route for producing epitaxial perovskite superlattice structures on (001)-oriented SrTiO₃/Si substrates

We report on the formation of epitaxial perovskite oxide superlattice structures by atomic layer deposition (ALD), which are integrated monolithically on Si wafers using a template layer of SrTiO₃deposited by hybrid molecular beam epitaxy. ALD film growth was carried out at 360 °C, which is significantly lower than the typical deposition temperatures for epitaxial perovskite thin films. The high control over the stacking sequence of different constituents is demonstrated in a series of (BaTiO₃)_m/(SrTiO₃)_nsuperlattices with variousm/ncycle ratios. All superlattice structures were coherently strained to the virtual substrate layer of SrTiO₃on Si. Irrespective of them/nsuperlattice sequence, SrTiO₃sublayers retain slight compressive strain which is transmitted to the BaTiO₃layers.