Unveiling the orientation growth mechanism and solar-blind response performance of β-Ga2O3 (100) film on SiC substrate with AlN buffer layer

Optimizing the orientation of β-Ga2O3 has emerged as an effective strategy to design high-performance β-Ga2O3 device, but the orientation growth mechanism and approach have not been revealed yet. Herein, by employing AlN buffer layer, the highly preferred orientation of β-Ga2O3 (100) film rather than (-201) film is realized on 4H-SiC substrate at low sputtering power and temperature. Because β-Ga2O3 (100) film exhibits a slower growth speed than (-201) film, the former possesses the higher dangling bond density and the lower nucleation energy, and a large conversion barrier exists between these two orientations. Moreover, the AlN buffer layer can suppress the surface oxidation of the 4H-SiC substrate and eliminate the strain of β-Ga2O3 (100) film, which further reduces the nucleation energy and enlarges the conversion barrier. Meanwhile, the AlN buffer layer can increase the oxygen vacancy formation energy and decrease the oxygen vacancy concentration of β-Ga2O3 (100) film. Consequently, the solar-blind photodetector based on the oriented film exhibits the outstanding detectivity of 1.22 × 1012 Jones and photo-to-dark current ratio of 1.11 × 105, which are the highest among the reported β-Ga2O3 solar-blind photodetector on the SiC substrate. Our results offer in-depth insights into the preferred orientation growth mechanism, and provide an effective way to design high-quality β-Ga2O3 (100) orientation film and high-performance solar-blind photodetector.