Formation of lateral quantum wells in vertical short-period superlattices by strain-induced lateral-layer ordering process

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Abstract
The lateral quantum wells formed in vertical (GaAs)n/(InAs)n and (GaP)n/(InP)n short-period superlattices (SPS) grown on nominally (100) InP and GaAs substrates, respectively, have been examined. The strain induced from the deviation of superlattice periodicity from na0 is the major driving force of the lateral modulation of the composition along the [110] direction, where the integer n is the number of monolayers of each binary compound within a period of SPS structure and a0 is the lattice constant of the substrate material. When the deviation of the superlattice periodicity from na0 is larger than ∼4%, both (GaAs)n/(InAs)n and (GaP)n/(InP)n ordered vertical SPS layers were found to have a lateral periodic modulation of composition with periodicities as small as ∼200 Å. This effect is enhanced when n was increased from 1 to 2.