Heterogeneous nucleation of misfit dislocations in InGaP/GaAs layers grown by MOVPE

The origin of misfit dislocations in MOVPE grown InGaP/GaAs epilayers in compression has been investigated by means of TEM observations. Several [011] 60degrees misfit dislocations were found to be associated with stacking faults which suggests that their nucleation was heterogeneous and occurred through reaction of the Shockley partials bordering the stacking faults probably assisted by the strain energy stored in the layers. The stacking faults might have originated at growth islands. An asymmetric distribution of the misfit dislocations was also observed. It was ascribed to the difference between the alpha and beta type of the 60degrees dislocations, with the alpha dislocations propagating easier as they have a higher mobility than the beta ones.