Metalorganic Chemical Vapor Deposition of (011) β-Ga ₂ O ₃ Films with 20 μm Drift Layer

Different from the (010) or (001) β-Ga 2 O 3 thin-film growths, we report the growth of high-quality (011) β-Ga 2 O 3 epitaxial films by metal–organic chemical vapor deposition (MOCVD) with thicknesses up to 20 μm. A series of β-Ga 2 O 3 films were grown at growth rates of 2.86 and 5.5 μm/h on (011) β-Ga 2 O 3 substrates using trimethylgallium (TMGa) and high-purity oxygen as precursors. Atomic force microscopy revealed extremely low root-mean-square (RMS) roughness across all samples, with values of 0.48–1.05 nm for film thicknesses up to 20 μm, representing the lowest reported roughness for as-grown β-Ga 2 O 3 films of comparable thickness and scan area (5 × 5 μm 2 ). X-ray diffraction confirmed excellent crystalline quality, with on-axis rocking curve full width at half-maximum (FWHM) values as low as 13.6 arcsec and off-axis values as low as 29.2 arcsec, revealing very low screw- and edge-type threading dislocation densities. Dent-type defect density, which increased with growth thickness, was significantly reduced at lower growth rates and further suppressed through the introduction of a buffer layer. Scanning transmission electron microscopy (STEM) imaging revealed a high crystalline quality of the as-grown films. Quantitative secondary ion mass spectrometry (SIMS) measured low background carbon and hydrogen levels along with minimal background silicon at or below the detection limit, even at growth rates up to ∼7.5 μm/h. The results from this work provide valuable guidance for the development of high-quality, thick β-Ga 2 O 3 films via MOCVD, which are essential for realizing high-performance vertical power devices.