STRAIN FROM MODIFIED INTERFACE COMPOSITIONS IN INGAAS INP SUPERLATTICES/

Thin strained regions have been inserted at the interfaces of lattice- matched InGaAs/lnP superlattices to assess growth conditions for tailo ring of localized compositional changes and for studying As-P intermix ing behavior during heterojunction growth. Also, precise growth rates of binary composition layers were determined from specially designed s uperlattices using strained layers of common anion compounds inserted periodically into InP and GaAs. Growth rates of fractional monolayers are found to be identical to thick layer growth rates. When thin InAs, GaAs, GaP, AlAs, or AIP layers were inserted at the InGaAs/InP hetero junctions, the measured strain at either one or both interfaces was eq ual to the strain predicted from the growth rate x time product. Exces s strain seen in some cases is due to a change in As-P intermixing and this component can be separated from the predicted strain. Insertion of Ga-compounds at the InP-grown-on-InGaAs interface causes interface roughening which degrades the superlattice. For all other compositions the thin, highly strained regions are not detrimental to the crystall ine quality of the periodic structure.