Ex-Situ Ozone Cleaning of SrTiO₃ Substrates for Molecular Beam Epitaxy

In molecular beam epitaxy synthesis of thin films, the quality of the substrate surface is crucial. The substrate not only provides a structural template for the deposited film, but the interaction between the film and the substrate itself determines emergent electronic properties. Therefore, it is critical to employ effective in-situ and ex-situ substrate cleaning techniques to ensure a clean substrate surface, which is necessary for high-quality film growth. Here, we report an investigation of the efficacy of cleaning with ozone as an ex-situ cleaning technique for widely used SrTiO₃ substrates. The substrates are ozone cleaned after etching and annealing. The carbon ratio on the substrate surface has been carefully examined using XPS to verify the efficacy of ozone cleaning.