Smooth surface morphology and high thickness uniformity heteroepitaxy of corundum-structured (α-) gallium oxide (Ga₂O₃) crystalline thin films on 100-mm diameter c-plane sapphire substrates were successfully demonstrated using vertical hot-wall mist chemical vapor deposition (CVD). The growth rate and surface morphology of the epitaxial layers were numerically and experimentally found to be dependent on the diameter of the precursor-diluted microdroplets approaching the substrate surface. Since the microdroplet is gradually evaporated while traveling through the furnace, the growth variables such as temperature, mist-flow velocity, and substrate position were tuned to obtain a suitable diameter of microdroplets approaching the substrate. In this study, the diameter of the approaching microdroplet was ≈2 μm, which was optimal for the smooth surface (root mean square roughness ≈1 nm) of α-Ga₂O₃ epitaxial layers with a growth rate of ≈230 nm/h. Due to the even flow of mist in the vertical furnace, high thickness uniformity of the α-Ga₂O₃ epitaxial layer is guaranteed on large-scale substrates, with a standard deviation of thickness as small as 28 nm, paving the way for highly reliable Ga₂O₃-based electric and optoelectronic devices.

刚玉结构 ( α- ) 氧化镓 (Ga ₂ O ₃ ) 晶体薄膜在 100 mm 直径c上的光滑表面形貌和高厚度均匀异质外延使用垂直热壁雾化学气相沉积 (CVD) 成功演示了平面蓝宝石衬底。通过数值和实验发现外延层的生长速率和表面形态取决于接近衬底表面的前体稀释微滴的直径。由于微滴在通过熔炉时逐渐蒸发，因此调整了温度、雾流速度和基板位置等生长变量，以获得接近基板的微滴的合适直径。在这项研究中，接近微滴的直径约为 2 μm，这对于α -Ga ₂ O ₃的光滑表面（均方根粗糙度 ≈1 nm）是最佳的生长速率约为 230 nm/h 的外延层。由于立式炉内雾流均匀，在大尺寸衬底上保证了α- Ga ₂ O ₃外延层的高度均匀性，厚度标准偏差小至28 nm，为高可靠的基于Ga ₂ O ₃的电气和光电器件。