Interfacial coherence and lateral indium segregation in thick InGaAs single heterostructures grown on GaAs substrates

Interfacial coherence in low-strained In/sub x/Ga/sub 1-x/As grown on GaAs substrates has been studied and the critical strains corresponding to layer thicknesses of 0.5, 1.0, and 2.0 /spl mu/m have been determined. The measured critical strains exceeded those expected from current theoretical models and the discrepancy could not be accounted for by including additional dislocation pinning due to either a Peierls force or a dislocation atmosphere. A new model of Lateral Indium Segregation (LIS) in the vicinity of a grown-in threading dislocation is proposed as an alternative explanation of our observations.