Determination of In concentration in InGaAs/GaAs 001 epilayers in the early stage of anisotropic stress relaxation

Abstract 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 In 0.13 Ga 0.87 As/GaAs (0 0 1) system with lattice misfit Δ a / a  = 9.3 × 10 −3 and the critical thickness t cMB  = 15 nm can be detected for layers of thickness exceeding t  ≅ 70 nm ≅ 4.5 t cMB . 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 Δ x  = ±0.01.