Single-phase κ-Ga2O3 films deposited by metal-organic chemical vapor deposition on GaAs and ternary BxGa(1-x)As templates

For the first time, single-phase κ-Ga2O3 films were grown on (001) p-type GaAs and BxGa(1-x)As /GaAs templates using Metal-Organic Chemical Vapor Deposition (MOCVD). The films were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). TEM investigations revealed a thin polycrystalline nucleation layer followed by well-oriented columnar growth of the κ-phase in the Ga2O3/GaAs sample, while segregation and diffusion effects in the ternary alloy led to boron accumulation on the template surface, which reacted with oxygen during the first stage of Ga2O3 deposition to form a thin amorphous oxide (a-BGaO) at the interface between Ga2O3 and the BGaAs/GaAs template. Again, columnar growth of large [001]-oriented grains of the orthorhombic κ-phase occurred on the amorphous nucleation layers, which resulted in a compact gallium oxide film. These polycrystalline or amorphous interlayers are important as they provide a suitable platform for growth of phase-pure orthorhombic κ-Ga2O3 on III-V cubic substrates. This work paves the way to the integration of κ-Ga2O3 and III-V semiconductors, for preparing heterojunctions for novel electronic and optoelectronic devices.