Determination of In concentration in InGaAs/GaAs 0Â 0Â 1 epilayers in the early stage of anisotropic stress relaxation

A method has been developed for determination of In concentration in strained layers of InGaAs/GaAs heterostructures. Chemical composition and lattice strain were evaluated from the reciprocal space maps obtained for asymmetric reflections. It was observed that beginning of relaxation of the In0.13Ga0.87As/GaAs (0 0 1) system with lattice misfit Δa/a = 9.3 × 10−3 and the critical thickness tcMB = 15 nm can be detected for layers of thickness exceeding t ≅ 70 nm ≅ 4.5tcMB. The principal relaxation mechanism is due to the slipping of 60° misfit dislocations on the tilted (1 1 1) glide planes. The accuracy of indium concentration measurements was estimated to Δx = ±0.01.