Single- and dual-variant atomic ordering in GaAsP compositionally graded buffers on GaP and Si substrates

On Si substrates, the GaAsP buffer displays dual-variant CuPtB ordering rather than single-variant ordering due to the surface step geometry. We discuss how dual-variant ordering leads to a variable glide force, and thus has a different impact on dislocation dynamics than single-variant ordering. Because the III-V on Si nucleation procedure determines the step geometry, it also influences the dislocation dynamics.