Study of p-type AlGaAs film grown on sapphire substrate using GaAs buffer layer

•Fabrication of the AlGaAs film grown on lattice-mismatched sapphire substrate.•Study of characteristics of AlGaAs film on sapphire substrate using a GaAs buffer layer.•Outstanding resistivity of p-AlGaAs film on sapphire substrate.

The characteristics of AlGaAs films grown directly on a lattice-mismatched Al2O3 substrate were investigated. Metal organic chemical vapor deposition based AlGaAs films were grown on a transparent Al2O3 substrate, using a GaAs film as the buffer layer for the post-growth of the AlGaAs film. It was found that a higher Al composition in AlGaAs film on the Al2O3 substrate was observed when GaAs buffer layer was thermally treated. Notably, a resistivity of 0.018 Ω/cm was obtained from the AlGaAs film grown on the Al2O3 substrate, almost equivalent to that for GaAs substrate. These results thus support the position that AlGaAs films grown on a transparent Al2O3 substrate can be attractive for use in solar cells or light-emitting diodes.