Rotation induced superlattice

摘要

This invention describes a multi-deposition system, whereby directing elemental or molecular source fluxes across a substrate in an asymmetrical manner and rotating the substrate at low rotation speeds, a superlattice is formed having a composition of A(x- DELTA x)B(1-(x- DELTA x))/A(x+ DELTA x)B(1-(x+ DELTA x) where DELTA x is a function of the nonuniform focusing of the elemental or molecular source fluxes A and B. More specifically, superlattices 18 are formed in the ternary and quaternary In(GaAl)As alloys on InP by molecular beam epitaxy without mechanical shuttering. The superlattice 18 is formed by nonuniformly directing the group III elements 22 and 24 onto the substrate 26 and rotating the substrate 26 across the beams. Periodic ordering is produced by rotation of the substrate 26 through a nonuniform distribution of source fluxes at the rotating substrate 26. The growth rate and substrate rotation rate together determine the superlattice period.