MOCVD Growth of (011) β-Ga2O3 Films: Defect Control and Device Implication

Abstract β-Ga2O3 is a promising ultrawide-bandgap semiconductor for high-power electronics; however, the realization of thick, low-defect drift layers at high growth rates remains challenging. In this work, metalorganic chemical vapor deposition (MOCVD) growth of (011) β-Ga2O3 drift layers on (011) β-Ga2O3 substrates is optimized using a far-injection showerhead reactor with trimethylgallium (TMGa) and O2 precursors. The effects of chemical pre-treatment, in situ oxygen annealing, wafer carrier rotation, and pulse-flow (PF) β-Ga2O3 interlayers are systematically investigated to correlate growth conditions with defect density. Chemical treatment B [18% HCl (10 min) + deionized (DI) water (10 min) + 49% HF (30 min)], combined with 1 h of in situ annealing at 900 °C, minimizes defect density under the selected growth conditions. Incorporation of a single PF1 interlayer (∼30 nm thick) further suppresses defect formation, reducing the defect density by more than one order of magnitude. Atomic force microscopy (AFM) reveals sub-nanometer root mean square (RMS) roughness and step-flow morphology for ∼11 μm thick films. High-resolution X-ray diffraction (XRD) rocking curves confirm the preserved crystalline quality. Field-plated Schottky barrier diodes (SBDs) fabricated on optimized films exhibit excellent forward conduction, low reverse leakage, and improved breakdown performance, highlighting the importance of defect control for high-performance vertical power devices.