Self-limiting process for the bismuth content in molecular beam epitaxial growth of Bi2Sr2CuOy thin films

A new technology utilizing a self-limiting mechanism for the Bi content is demonstrated for Bi2Sr2CuOy (2201) thin film growth by an atomic layer controlled molecular beam epitaxy. This technology is based on peculiar behavior of the Bi sticking coefficient that depends on the kinds of oxide thin films to be grown. When Bi atoms are supplied in excess with ozone molecular beam, only Bi atoms, being necessary for forming the structural unit (2201 half unit cell), are just incorporated in the film. Surplus Bi is reevaporated from the surface. Using this technique, high quality 2201 thin films are obtained with good reproducibility.