The role of climb and glide in misfit relief of InGaAs/GaAs(111)B heterostructures

The plastic relaxation of InGaAs/GaAs(111)B quantum wells (QWs) is investigated. Critical layer thickness (CLT) models based on the theory of Matthews–Blakeslee have been applied, assuming that dislocations glide from the substrate. We have observed that when the In-content is above 0.25, a three-pointed star-shaped misfit dislocation (MD) configuration appears. A detailed analysis has shown that this configuration cannot originate from the glide of pre-existing dislocations. Instead, these MDs are generated by climb from an initial nucleus. A modified Matthews–Blakeslee model including an osmotic force component is proposed. The resulting revised CLT depends on the departure of the vacancy concentration from its equilibrium.