A finite-element study of strain fields in vertically aligned InAs islandsin GaAs

Finite-element calculations are used to study strain fields in vertically a ligned InAs islands in GaAs. Such strain fields are found to be quite diffe rent from those of uncovered islands and nearly insensitive to the position of the island in the stacking. The driving force for vertically self-organ ized growth is known to be the interacting strain fields induced by the isl ands. The calculation of strain fields by the finite-element method makes i t possible to model the correlations between adjacent InAs layers. A kineti c approach based on the effect of strain on surface diffusion is first prop osed. A thermodynamic model is then analyzed to predict local island nuclea tion probabilities. Pairing probabilities of correlation between stacked is lands, first calculated in the case of the InAs/GaAs system, are extended t o the case of III-V semiconductors with a cubic crystalline structure. They are shown to be essentially dependent both on the ratio between the spacer layer thickness and the island height and on the lattice mismatch between islands and spacer layers. (C) 1999 American Institute of Physics. [S0021-8 979(99)08216-X].