Solution Monolayer Epitaxy for Tunable Atomically Sharp Oxide Interfaces

Interfaces play an important role in a variety of devices including transistors, solar cells, and memory components. Atomically sharp interfaces are essential to avoid charge traps that hamper efficient device operation. Sharp interfaces usually require thin-film fabrication techniques involving ultrahigh vacuum and high substrate temperatures. A new self-limiting wet chemical process for deposition of epitaxial layers from alkoxide precursors is presented. This method is fast, cheap, and yields perfect interfaces as validated by various analysis techniques. It allows the growth of heterostructures with half-unit-cell resolution. The method is demonstrated by designing a hole-type oxide interface SrTiO₃/BaO/LaAlO₃. It is shown that transport through this interface exhibits properties of mixed electron–hole contributions with hole mobility exceeding that of electrons.