氧化镓同质外延及二维"台阶流"生长研究OA北大核心

The achievement of single crystalline gallium oxide(Ga2O3)homoepitaxial layers with atomic-level smoothness is fundamental for the fabrication of high-performance Ga2O3-based power electronics or ultraviolet photodetectors.In this study,metal organic vapor phase epitaxy(MOVPE)technique was employed to comprehensively control the thermodynamic conditions and kinetic factors of epitaxial growth,resulting in the production of unintentionally doped,device-grade Ga2O3 single crystal films with a thickness of 1.0 μm on Ga2O3 substrates.Characterizations of the Ga2O3 samples were performed to investigate phase composition,surface morphology,crystal quality,and electrical properties.The Ga2O3 homoepilayer exhibits a single β phase with a preferential orientation matching the(100)plane of the substrate.Atomic force microscopy(AFM)analysis reveals a typical step-flow morphology,with a surface roughness of 0.166 nm and a step height of 0.6 nm(a/2),indicating atomic-level smoothness.High-resolution X-ray diffraction(HRXRD)rocking curve analysis was conducted to further evaluate the crystallinity of the Ga2O3 epilayers.The full width at half maximum(FWHM)of the epilayers is lower than that of the single crystal substrate,indicating superior quality of the Ga2O3 epilayers grown on the lattice-matched substrate.Hall effect measurements indicate an electron mobility of 92.1 cm2/(V·s)and a carrier concentration of 2.65 x 1016 cm-3.Our results demonstrate that high-growth-rate 2D step-flow growth on commonly used non-intentionally miscut substrates can be achieved as long as the critical thermodynamic conditions,such as temperature,pressure,and the Ⅵ/Ⅲratio-are finely tuned to ensure that the lateral diffusion rate of the core kinetic parameters is sufficiently greater than the vertical deposition rate.The exceptional crystal quality and electrical properties highlight the significant potential of these(100)-oriented homoepitaxial films in the development of high-performance Ga2O3-based power electronics.