A gaAs surface after its contact with an undersaturated AlGaAs liquid. Observation after anodic oxidation

When an undersaturated liquid phase containing Al contacts with a GaAs crystal, a AlGaAs dividing layer (DL) forms at the solid surface. The anodic oxidation of such a surface reveals an inhomogeneity of the DL in thickness or composition because a contrast of anodic oxide colours appears. The different colour pictures reflect the complex morphology of the dissolved surfaces on the ledges of which the AlGaAs solid solution epitaxially deposits. An explanation proposal is made of the AlGaAs deposition on the GaAs substrate when the latter is in contact with the undersaturated AlGaAs melt.