IMPROVED SIZE HOMOGENEITY OF INP-ON-GAINP STRANSKI-KRASTANOW ISLANDS BY GROWTH ON A THIN GAP INTERFACE LAYER

Coherent InP nano-sized islands, embedded into GaInP, have been grown by metal-organic vapour phase epitaxy using the Stranski-Krastanow growth mode. Photoluminescence, atomic force microscopy and transmission electron microscopy studies show that the insertion of a thin similar to 4 monolayer thick GaP layer affects the critical thickness of the subsequently deposited two-dimensional InP wetting layer, increasing it from similar to 1.5 monolayers (without an inserted GaP layer) to similar to 2.5 monolayers (with an inserted GaP layer). We demonstrate that the inserted GaP layer affects also the island formation. The bimodal size distribution of Stranski-Krastanow islands, typical for low InP coverages, can be overcome without island coalescence by deposition on top of the thin GaP layer, where a coverage of InP of about 3.5-4.5 monolayers results in the formation of almost only the larger, fully developed, pyramidal islands, Annealing experiments at growth temperature of 580 degrees C show that these islands (base area approximate to 40 x 50 nm(2), height approximate to 10-15 nm, surface density approximate to(1-2)x10(9) cm(-2)) are rather stable in a time-scale over several minutes before they slowly undergo an Ostwald ripening process.