As cluster array formation in GaAs grown by molecular-beam epitaxy at a low temperature and δ-doped with phosphorus

GaAs films delta-doped with phosphorus (one monolayer) were grown by molecular beam epitaxy at a temperature of 200A degrees C (LT-GaAs), isochronally annealed at 400, 500 or 600A degrees C, and studied by transmission electron microscopy. Analysis of the moir, fringes in the electron microscopy images of the clusters formed upon annealing revealed that their microstructure and orientation relationship correspond to the parameters of pure As clusters in GaAs; hence, there is no considerable incorporation of phosphorus from the matrix into the forming clusters during precipitation of excess As. Examination of the cluster's spatial distribution across the LT-GaAs films showed no variation in the cluster array's concentration near the P A degrees-layers for the used growth and annealing conditions. Thus, phosphorus, being introduced into a LT-GaAs film in the form of A degrees-layers, behaves as the isovalent Al impurity and differs from such isovalent impurities as In and Sb by the effect on the spatial distribution of As clusters.