Low-temperature photoluminescence topography of MOCVD-grown InGaP, AlGaAs and AlGaAs/GaAs single quantum wells

Low-temperature photoluminescence topography has been used to monitor local variations in composition of In_1-yGa_yP and Al_xGa_1-xAs layers which were grown lattice-matched on semi-insulating LEC GaAs substrates by MOCVD. Whereas the in content varies by less than +or-1% over the whole 2 inch water, the Al concentration changes by about +or-3%. In Al_xGa_1-xAs/GaAs quantum well (QW) structures the dependence of photoluminescence energy on QW thickness is used to estimate spatial variations in the thickness of the well material. The resulting thickness topogram is compared with numerical simulations of the gas flow profile in the MOCVD reactor.