Edge-Dependent Step-Flow Growth Mechanism in β-Ga2O3 (100) Facet at the Atomic Level

Q Li and JL Zhao and N Lin and XF Cheng and X Zhao and ZJ Liu and ZT Jia and MY Hua, JOURNAL OF PHYSICAL CHEMISTRY LETTERS, 16, 5101-5108 (2025).

DOI: 10.1021/acs.jpclett.5c00461

Homoepitaxial step-flow growth of high-quality beta-Ga2O3 thin films is essential for the advancement of high-performance Ga2O3-based devices. In this work, the step-flow growth mechanism of the beta-Ga2O3 (100) facet is explored by machine-learning molecular dynamics simulations and density functional theory calculations. Our results reveal that Ga adatoms and Ga-O adatom pairs, with their high mobility, are the primary atomic species responsible for efficient surface migration on the (100) facet. The asymmetric monoclinic structure of beta-Ga2O3 induces a distinct two-stage Ehrlich-Schwoebel barrier for Ga adatoms at the 00-1 step edge, contributing to the suppression of double-step and hillock formation. Furthermore, a miscut toward 00-1 does not induce the nucleation of stable twin boundaries, whereas a miscut toward 001 leads to the spontaneous formation of twin boundaries. This research provides meaningful insights not only for high-quality beta-Ga2O3 homoepitaxy but also the step-flow growth mechanism of other similar systems.

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