A technology for growing a single-crystal thin film according to the
crystal structures of the substrate.
Forming thin-film crystals conforming to the crystalline
orientation of the substrate results in a tightly bonded thin film with stable electrical
characteristics. Epitaxy is divided into solid phase, liquid phase, and vapor phase processes,
depending on the state of the substance to form a film. The first epitaxy was realized in liquid
phase. Then molecular beam epitaxy (MBE) technology was developed as one kind of vapor phase growth
capable of controlling the film thickness at a single atomic layer using ultra-high vacuum
technology. Superlattices have been produced by this method.