Forces between cavities and dislocations and their influence on semiconductor microstructures

An approximate continuum method for computing the energy of interaction bet ween cavities and strain fields in complex configurations is described and tested by comparison with results for simple, exactly solvable cases. The m ethod is then used to examine semiquantitatively the effective forces betwe en cavities and screw and edge dislocations, taking into account the effect s of surface tension and pressurized gas within the cavity. The discussion encompasses not only local interactions involving individual cavities, but also the combined forces acting upon dislocations in the vicinity of multip le cavities and simultaneously within range of external-surface image force s. The results are used to interpret a range of observed microstructures in semiconductors and to assess the possible exploitation of cavity-dislocati on binding for dislocation control in Si-Ge heteroepitaxial structures. (C) 1999 American Institute of Physics. [S0021-8979(99)05518-8].