EVIDENCE FOR NONUNIFORM INTERFACE THICKNESS IN STRAINED INGAAS INP QUANTUM-WELLS/

Advanced materials for optoelectronic device production increasingly u se ultrathin (a few monolayers thick) quantum wells of InGaAs lattice matched to InP. For instance, in the particular case of optical fiber communications using wavelengths of 1.3 mum, the standard requirement is to grow active layers about 8 monolayers thick, with abrupt interfa ces and good uniformity across a 2 in wafer. In this case, to combine mass production techniques with a high degree of integration, low-pres sure, metallo-organic vapor phase epitaxy (LP-MOVPE) seems to be the m ost promising technique. However, because LP-MOVPE is very sensitive t o the gas switching and growth interruption sequences, finite interfac e layers develop and modify the optical properties of the devices. In this work, we demonstrate that such interfaces are not uniform but dep end on the initial degree of coverage with foreign species. In the par ticular case of InP/InGaAs, we find that the typical dispersion (for a given series of samples) is of the order of 0.5 Langmuir.