SELF-ORGANIZED LATERAL SUPERLATTICE FORMATION BY VERTICAL EXCHANGE-REACTIONS

The formation of a self-organized lateral superlattice has been observed in (AlAs)m(GaAs)n short-period superlattices grown on vicinal GaAs(100) surfaces by molecular beam epitaxy. The lateral period is given by the substrate step periodicity. It is proposed that a vertical exchange reaction between the Al and the Ga at the growing interface, in conjunction with step-flow behavior leads to a spontaneous lateral segregation. Monte Carlo simulations within a one-dimensional growth model are used to substantiate the experimental findings. The proposed mechanism may be a kinetic pathway for lateral ordering in other materials systems.