Extending the kinetic and thermodynamic limits of molecular-beam epitaxy utilizing suboxide sources or metal-oxide catalyzed epitaxy

Patrick Vogt; Felix V. E. Hensling; Kathy Azizie; Jonathan P. McCandless; Jisung Park; Kursti DeLello; David A. Muller; Huili G. Xing; Debdeep Jena; Darrell G. Schlom

paper

Extending the kinetic and thermodynamic limits of molecular-beam epitaxy utilizing suboxide sources or metal-oxide catalyzed epitaxy

arXiv:2112.05022

Abstract

We observe a catalytic mechanism during the growth of III-O and IV-O materials by suboxide molecular-beam epitaxy ( $S$ -MBE). By supplying the molecular catalysts In $_{2}$ O and SnO we increase the growth rates of Ga $_{2}$ O $_{3}$ and In $_{2}$ O $_{3}$ . This catalytic action is explained by a metastable adlayer $A$ , which increases the reaction probability of the reactants Ga $_{2}$ O and In $_{2}$ O with active atomic oxygen, leading to an increase of the growth rates of Ga $_{2}$ O $_{3}$ and In $_{2}$ O $_{3}$ . We derive a model for the growth of binary III-O and IV-O materials by $S$ -MBE and apply these findings to a generalized catalytic description for metal-oxide catalyzed epitaxy (MOCATAXY), applicable to elemental and molecular catalysts. We derive a mathematical description of $S$ -MBE and MOCATAXY providing a computational framework to set growth parameters in previously inaccessible kinetic and thermodynamic growth regimes when using the aforementioned catalysis. Our results indicate MOCATAXY takes place with a suboxide catalyst rather than with an elemental catalyst. As a result of the growth regimes achieved, we demonstrate a Ga $_{2}$ O $_{3}$ /Al $_{2}$ O $_{3}$ heterostructure with unrivaled crystalline quality, paving the way to the preparation of oxide device structures with unprecedented perfection.