INTERFACIAL PROPERTIES OF VERY THIN GAINAS/INP QUANTUM-WELL STRUCTURES GROWN BY METALORGANIC VAPOR-PHASE EPITAXY

GaInAs/InP single quantum well structures with thicknesses below 5 nm were grown by metalorganic vapor phase epitaxy at reduced pressure. The sharpness of the heterojunctions in this III/V system is found to be strongly dependent on the applied gas switching sequence between the growth of the two materials caused by As carry over after GaInAs and by group V atom exchange at the surface during a hydride stabilized growth interruption. The photoluminescence properties can be improved by adding intermediate monolayers of InAsP between InP and GaInAs and GaInAsP between GaInAs and InP. The photoluminescence of very thin quantum wells is split into multiplets due to the formation of growth islands at the interface. Size and lateral distribution of these islands have been observed directly by cathodoluminescence analysis. On the other hand, transmission electron microscopy measurements show that the interfaces within the growth island regions are not atomically smooth but of a certain roughness. Small microislands with diameters of a few lattice constants form the "internal" interface structure.