Competing relaxation mechanisms in strained semiconducting and superconducting films

A theoretical model is suggested which describes the crossover from the disclination (rotational) mechanism of misfit stress relaxation to the dislocation (translational) mechanism in strained solid films, with the emphasis on the case of semiconducting and high-transition-temperature superconducting films. In the framework of the model, the ranges of parameters (film thickness, characteristics of disclination arrangement, misfit parameter) of disclinated films for which the generation of misfit dislocations is energetically favourable are calculated. The specific features of films with misfit disclinations and dislocations are discussed in relation to the technologically interesting possibility of exploiting either disclinated or dislocated films for applications.