Suppression of Hillock Defects on (010) β-Ga₂O₃ Homoepitaxial Layer Growth via Halide Vapor Phase Epitaxy

Hillock, a type of surface defect with small mounds or protrusion morphologies, can significantly impair the flatness and uniformity of β phase gallium oxide (β-Ga2O3) epitaxy, particularly on the (010) plane. Herein, a high-quality, hillock-free (010) β-Ga2O3 homogeneous layer with a thickness of ∼10 μm was successfully grown by halide vapor phase epitaxy (HVPE). The growth mode and hillock structure were thoroughly investigated via optical microscopy (OM), confocal laser scanning microscopy (CLSM), X-ray rocking curve (XRC) analysis, and transmission electron microscopy (TEM). The results indicate that these hillocks are polycrystalline particles, which generate along the <001> direction with specific intersection planes of (610) and (61̅0). By adjusting the flow of O2 while fixing the flow of HCl, a precise hillock hindrance method was implemented, resulting in a smoother (010) epitaxy surface at VI/III ratios below 18. This work offers a new perspective on the origin and suppression method of the hillock defect on HVPE (010) β-Ga2O3 layers, paving the path to fabricate high-performance power devices.