Silicon-Integrated Transition Metal Oxide Thin Film Quantum Structures

While the SrTiO₃/LaAlO₃ (STO/LAO) system has garnered widespread attention since the discovery of a two-dimensional electron gas at the interface of these two band insulators, recent efforts have instead focused on its optical properties. The huge 2.4 eV conduction band offset between STO and LAO allows for charge confinement in STO quantum wells and the optical and electrical modulation of carriers between confined states. Such heterostructures could find use in a multitude of next-generation electrical, optical, and electro-optical devices. However, the technological relevance of such devices hinges on the ability to successfully integrate high-quality STO/LAO quantum structures with silicon. Here, we demonstrate the monolithic integration of high-quality STO/LAO multiple quantum wells on silicon (001) with molecular beam epitaxy. We present electron diffraction, X-ray diffraction and electron microscopy studies establishing the excellent uniformity and crystalline quality with which such heterostructures can be fabricated. Finally, we present examples of how silicon-integrated STO/LAO quantum structures could be used in device fabrication.