Interface strain in InGaAs-InP superlattices

Strain has been measured within (001) oriented OMVPE grown multilayer superlattices consisting of thin As-compound layers in InP and thin P-compound layers in GaAs. From the strain behavior, it is interpreted that As rapidly replaces P on an InP surface exposed to AsH3 and P slowly replaces As on a As-terminated surface exposed to PH,. This results in incorporation of an InAs-like strain in InP whose magnitude depends on the nature of the As-terminated surface. At growth temperatures above 600 degrees C, the strain is equivalent to about one monolayer of InAs; while below 600 degrees C, it is equivalent to two monolayers of InAs. PH3 interaction with GaAs surfaces is sufficiently slow that GaP-like strain is observed only when deliberate interrupts under PH3 are introduced. GaP grown on GaAs at 650 degrees C is found to incorporate enough residual As to sustain a layer composition of GaAs5P5 over the first several monolayers.