This article concerns the microstructure of self-assembled ErAs islands embedded in GaAs. The material is grown by molecular beam epitaxy. The nucleation of ErAs on GaAs occurs in an island growth mode leading to spontaneous formation of nanometer-sized islands. Several layers of ErAs islands separated by GaAs can be stacked on top of each other to form a superlattice. A series of such samples were grown with different depositions of ErAs at a growth temperature of 535°C. The microstructure of these samples was investigated by x-ray diffraction and transmission electron microscopy. We find that initially isolated ErAs islands with a diameter of 2 nm are nucleated. With increasing ErAs deposition, these islands branch out and form extended structures. The samples are coherent in growth directions for ErAs depositions up to 1.8 monolayers. At higher ErAs depositions defects are incorporated into the GaAs matrix.

This article concerns the growth-temperature dependence of the microstructure of ErAs islands embedded in GaAs. The material was grown by molecular-beam epitaxy. The nucleation of ErAs on GaAs occurs in an island growth mode leading to spontaneous formation of nanometer-sized islands. Multiple layers of ErAs islands separated by GaAs can be stacked on top of each other to form a superlattice along the growth direction. A series of four such samples were grown at growth temperatures of 480°C, 535°C, 580°C, and 630°C. For all samples, 1.8 monolayers of ErAs were deposited in each layer of the superlattices. The microstructure of these samples was investigated by x-ray diffraction and transmission electron microscopy. We find that single crystallinity was maintained across the layers of ErAs islands at the growth temperatures of 535°C, 580°C, and 630°C. At the growth temperature of 480°C, however, the sample was not single crystalline. The GaAs matrix of the sample was defective. With increasing growth temperature, the size of the ErAs islands increased and the areal density of the ErAs islands decreased. The size increase is due to an increasing lateral ͑in-plane͒ dimension; the height of the islands is essentially unchanged.