Plastic relaxation and coherency limit in uncapped multi-faceted InAs/GaAs(001) nanoislands Available to Purchase

Plastic relaxation and coherency limit in realistic uncapped InAs/GaAs(001) pyramid and dome nanoislands are investigated in depth. Due to geometrical symmetry determined by {1 3 7} facets, typical 60° straight dislocations, along [−1 1 0] and [−1 −1 0], are considered separately. We adopt both P-K approach and full finite element method (FEM) model to predict the equilibrium position of misfit dislocation in pure InAs nanoislands. Consistent results are obtained: the positions of two dislocations for maximum strain relaxation are different in pyramid while the positions are same in dome. Based on the full FEM model, the critical dimensions of coherency are evaluated by comparing total energy stored in coherent and dislocated nanoislands. The results indicate that misfit dislocation along [−1 1 0] should generate first in pyramid, while almost identical critical volumes of dome shapes can be expected for both dislocation configurations. Moreover, the critical volume of dome nanoisland rises as the aspect ratio increases.