Antiphase boundaries in GaAs layers on Si and Ge

A systematic study of the formation of antiphase boundaries and their properties in GaAs layers grown by metalorganic chemical vapor deposition (MOCVD) on Si 1 − x Ge x /Si (001) and Ge (001) substrates has been performed by chemical etching, scanning and transmission electron microscopy. The main attention is paid to the peculiarities of antiphase boundary propagation through the epitaxial layer and the interaction of boundaries with dislocations. Three various antiphase boundary configurations are determined. These experimentall observed configurations are in good agreement with those deduced from formal analysis of heterostructure crystal lattice. A connection of the boundary geometric configurations with the vapor phase composition oscillations in the crystallization zone is proposed. The stable [As]/[Ga] ratio in the vapor phase leads to the annihilation of inclined antiphase boundaries, whereas the concentration oscillations cause the formation of zigzag-like boundaries which propagate through the epitaxial layer.