Dislocation formation mechanism in strained InxGa1−xAs islands grown on GaAs(001) substrates

Abstract

The formation mechanism of misfit dislocations in lattice-mismatched InxGa1−xAs epilayers (0.2≤x≤1) grown on GaAs substrates has been investigated experimentally. The results suggest that 1/3〈111〉 Frank partial dislocations are grown-in at island edges in highly lattice-mismatched epilayers (x≥0.4). Then after further island growth 90° Shockley partial dislocations are nucleated to remove the stacking faults, reacting with the Frank partials to form complete 90° dislocations. An atomic model is proposed to explain the formation mechanism of the Frank partial dislocation. This model could explain the observed change in the dominant type of dislocation from the 60° at small mismatches to 90° edge dislocations at large lattice mismatches.