Influence of substrate atomic symmetry on the epitaxy and rotational domain formation of κ-Ga2O3

초록

This study systematically explores the structural factors influencing kappa-phase gallium oxide (kappa-Ga2O3) thin film growth and domain formation on non-basal plane substrates. Accordingly, we grew kappa-Ga2O3 thin films using mist chemical vapor deposition on both basal and non-basal plane sapphire (c-, a-, m-, and r-plane) and GaN (c- and m-plane) substrates for analysis. Crystallinity, orientation, and domain structures were assessed by X-ray diffraction including 20-w scans, rocking curves, and (p-scans. On c- and a-plane sapphire and GaN substrates, kappa-Ga2O3 with c-axis orientation was selectively stabilized, whereas alpha-Ga2O3 predominantly formed on r- and mplane sapphire. Regardless of substrate symmetry, all kappa-Ga2O3 films exhibited persistent three-fold rotational domains, highlighting the limitations of current substrate configurations. These results demonstrate the significant influence of substrate atomic arrangement on phase stability and domain control, emphasizing the need for advanced substrate engineering to realize single-domain kappa-Ga2O3 thin films with improved crystalline quality.

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