Interpretation of x-ray rocking-curve broadening caused by lattice relaxation around metastable point defects

The x-ray rocking-curve broadening accompanying the transfer to and from the metastable state of EL2 and DX centers in GaAs and ${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As has recently been observed experimentally [Leszczynski et al., Semicond. Sci. Technol. 6, B66 (1991)]. This paper gives a more quantitative analysis of the experimental results. Computer simulations of rocking curves based on the dynamical theory of x-ray diffraction for various models of the real crystal structure made it possible to evaluate the conditions in which the lattice relaxation could be observed in experiment. The general conclusion is that in all the materials examined, the inhomogeneities played a decisive role. The possible range of the inhomogeneities and the strains around EL2 and DX centers is discussed in relation to their microscopic models.