Metalorganic chemical vapor deposition of β-(Al)Ga2O3 on (001) β-Ga2O3 substrates

β-Ga2O3 and its alloys are promising for next-generation high-power electronic devices, but realizing high-quality thick epitaxial layers with smooth morphology at high growth rates remains a major challenge. In this study, we systematically investigated the metalorganic chemical vapor deposition (MOCVD) growth of β-Ga2O3 on edge-defined film-fed growth (EFG, Sn doped) and vertical bridgman (VB, Fe doped) (001) β-Ga2O3 substrates. (001) β-Ga2O3 films grown on both substrates show similar cracking issue. Films grown on EFG substrates show lower atomic force microscopy roughness as compared to those grown on VB substrates. X-ray diffraction (XRD) measurements indicate lower crystalline quality in films grown on VB substrates compared to films grown on EFG substrates. XRD rocking curves also illustrate that films grown on VB substrates have higher structural anisotropy. From cross-sectional scanning transmission electron microscopy (STEM) imaging, surface reconstruction occurred at the growth interface for both EFG and VB substrates. MOCVD growth of β-(Al0.0625Ga0.9375)2O3 on (001) β-Ga2O3 substrates indicate crack-free layers can be grown up to 6 μm at a growth rate of 4.5 μm/h. STEM atomic-scale analysis revealed a uniform Al-distributed interfacial layer at the growth interface followed with an Al-segregated region aligning along the (1¯01) plane. Electrical measurements revealed low mobility in thick (001) AlGaO layers which is due to crystal rotation and Al segregation. These results provide understanding of MOCVD growth of (001) β-Ga2O3 and (001) β-(AlxGa1−x)2O3 films at fast growth rates and insights into the interplay of growth chemistry, substrate selection, and alloy incorporation.