Over-relaxation of misfit strain in heavily carbon-doped GaAs grown by metalorganic molecular beam epitaxy after annealing

Using double crystal x-ray diffractometry (XRD) and transmission electron microscopy (TEM), the annealing effects on heavily carbon-doped GaAs films were studied. From isochronal annealing, the evolution of compressive strain in carbon-doped GaAs films was observed by XRD. From cross-sectional TEM, unusual misfit dislocations with extra-half planes on the GaAs side were observed in the sample annealed at 900°C for 30 min in addition to normal misfit dislocations with extra-half planes on the film side. A possible mechanism for the formation of such misfit dislocations is proposed based on the over-relaxation of misfit strain in the film.