In–Ga intermixing in low-temperature grown GaAs delta doped with In

Abstract

Low-temperature grown GaAs films with indium delta layers are studied by transmission electron microscopy. The delta layers in the as-grown film are found to be as thick as four monolayers (ML) independently of a nominal In deposit of 0.5 or 1 ML, a thickness which reflects the film surface roughness during the low-temperature growth. A pronounced In–Ga intermixing is observed in the films subjected to 500–700 °C isochronal anneals. The In–Ga interdiffusion diffusivity is evaluated. The effective activation energy for In–Ga interdiffusion is found to be 1.1±0.3 eV which is significantly smaller than a value of 1.93 eV for a stoichiometric GaAs. The difference seems to result from a loss of the gallium vacancy supersaturation upon annealing, and is consistent with an annihilation enthalpy of 0.8 eV.