Transmission electron microscopy analysis of the shape and size of semiconductor quantum dots

Strong-beam diffraction contrast in transmission electron microscopy (TEM) associated with quantum dots (coherently strained islands) of InAs deposited on a GaAs substrate is analysed. The elastic displacement field associated with each quantum dot is determined using the finite-element method and the dynamical diffraction theory is subsequently used to simulate the corresponding TEM image contrast. The excellent match observed between simulated and experimental twobeam dynamical images shows that the shape of quantum dots can be readily determined by a geometrical analysis of these images and that the size of the dots can also be obtained under somewhat more restrictive conditions.