Computation of the strain field generated by dislocations with a position-dependent Burgers' vector distribution

A new phenomenon of strain relaxation will be presented. Ln a series of In, Gal-ps graded composition buffer layers grown on well cut (001) GaAs substr ates, a curvature of the epilayer lattice has been found, i.e. a tilt of th e epilayer lattice orientation with respect to the substrate which varies c oherently along the sample surface on the scale of several mm. The most rec ent data analysis performed on a buffer layer compositionally graded with a six-step profile shows also a thickness functional dependence of the curva ture. The epilayer lattice curvature has been attributed to a coherent late ral distribution of the Burgers' vectors. An analytical model has been deve loped in the framework of the continuum elasticity theory to compute the re lated strain field. The results show small but unexpected contributions to the parallel strain. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.