Involvement of image forces in dynamics of epitaxial dislocation arrays

We study the collective vibrational dynamics of epitaxial dislocation arrays in strained-layer structures grown beyond the critical thickness. Calculations are carried out in the frame of the isotropic elasticity theory enabling one to reveal the nature of dynamical correlations originating in the assembly of fluctuating dislocation lines. It is shown that due to shielding capabilities of image interactions the elastic response of a dislocation net can be described by means of an effective stiffness modulus. We find that the spectrum of collective excitations in the dislocation population exhibits sensitive dependence not only on the interface mismatch, but also varies with the epilayer thickness. The obtained results are used to determine the mean-square fluctuations in the dislocation ensemble and to characterize its entropy.