Epitaxial Oxides on Glass: A Platform for Integrated Oxide Devices

The fabrication of epitaxial, ultrathin SrTiO₃ (STO) on thick SiO₂ without the need for complicated wafer-bonding processes has been demonstrated. The resulting transition metal oxide (TMO)-on-glass layer stack is analogous to traditional silicon-on-insulator (SOI) wafers, where the crystalline device silicon layer of SOI has been replaced by a crystalline functional TMO layer. Fabrication starts with ultrathin body SOI on which crystalline STO is grown epitaxially by molecular beam epitaxy. The device silicon layer is subsequently fully oxidized by ex situ high-temperature dry O₂ annealing, as confirmed by X-ray photoelectron spectroscopy, X-ray reflectivity, and high-resolution electron microscopy. STO maintains its epitaxial registry to the carrier silicon substrate after annealing, and no evidence for degradation of the STO crystalline quality as a result of the TMO-on-glass fabrication process is observed. The ease of fabricating the TMO-on-glass platform without the need for wafer bonding will enable rapid progress in the development of state-of-the-art TMO-based electronic and photonic devices.