A study of the evolution process of antiphase boundaries in GaAs on Si

Abstract

A study by high resolution electron microscopy and conventional transmission electron microscopy of the process of closure of antiphase boundaries (APB) in atomic layer molecular beam epitaxy (ALMBE) grown GaAs on silicon is reported. A parallelepipedical shape, closed at the top by another boundary with a semispheric shape, is proposed for the during growth suppressed APBs in GaAs epilayers. Antiphase boundaries are mostly located in {100} plans. Sixty degree dislocations are involved in the process of bending of APBs from {110} to {11n} planes; this bending is the initial step which must take place to get a single domain by interaction of two APBs. The proposed shape for closed APBs is in good agreement with the quasi two-dimensional growth observed for GaAs grown on silicon by ALMBE.