Realization of closed-loop optimization of epitaxial titanium nitride thin-film growth via machine learning
I. Ohkubo, Zhufeng Hou, Jiyeon N. Lee, T. Aizawa, Mikk Lippmaa, Toyohiro Chikyow, Koji Tsuda, Takao Mori
Abstract
Closed-loop optimization of epitaxial titanium nitride (TiN) thin-film growth was accomplished using metal-organic molecular beam epitaxy (MO-MBE) combined with a Bayesian machine-learning technique and reduced the required number of thin-film growth experiments. Epitaxial TiN thin films grown under the process conditions optimized by the Bayesian approach exhibited abrupt metal–superconductor transitions above 5 K, demonstrating a new approach to the efficient development of less-studied materials, such as transition metal nitrides. The combination of the thin-film growth technique and Bayesian approach is expected to pave the way toward accelerating the development of the automated operation of thin-film growth apparatuses.