Moiré-like fringes in transmission electron microscopy images of coherently strained semiconductor islands

Moire-like fringes are observed in transmission electron microscopy images of coherently strained semiconductor islands. They are due to the misfit between the island and the underlying substrate and they can be used to determine the chemical composition of these islands by measuring the fringe spacing of the Moire-like system. The results of a simple kinematical analysis are shown to be very similar to those of dynamical two-beam calculations. The interest of the kinematical analysis is that, contrary to the dynamical two-beam calculations, it makes it possible to understand how Moire-like fringes are related to parallel Moire fringes and how the fringe spacing is related to the strain field at the apex of the island, and then to the mean composition of the island.