Lattice curvature generation in graded InxGa1-xAs/GaAs buffer layers

Position dependent lattice tilts in InGaAs/GaAs(001) compositionally graded buffer layers are investigated. The lateral dependence of the tilt defines a concave buffer layer curvature of up to 3 deg cm(-1). The buffer layer c urvature is associated with a distribution of the misfit dislocation Burger s vectors that varies nearly linearly across the sample. The origin of this peculiar distribution is discussed and is explained in terms of a Burgers- vector selection rule, which governs the cross slip of gliding threading di slocations and that has been experimentally observed by Capano in Phys. Rev . B 45, 11 768 (1992). A quantitative model of lattice curvature formation is presented that satisfactorily accounts for the main features of the obse rved buffer layer curvature.