Strain relaxation in graded composition InxGa1-xAs/GaAs buffer layers

A model to compute the strain relaxation rate in InxGa1-xAs/GaAs single lay ers has been tested on several compositionally graded buffer layers. The ex istence of a critical elastic energy has been assumed as a criterion for th e generation of new misfit dislocations. The surface strain accuracy result s are within 2.5x10(-4). The influence of different grading laws and growth conditions on residual strain, threading dislocation density, misfit dislo cation confinement, and surface morphology has been studied. The probabilit y of dislocation interaction and work hardening has been shown to strongly influence the mobility and the generation rate of the dislocations. Optimiz ation of the growth conditions removes residual strain asymmetries and smoo thes the surface roughness. (C) 1999 American Institute of Physics. [S0021- 8979(99)01421-8].