  We present in this work a simple Quantum Well (QW) structure consisting of
GaAs wells with AlGaAs barriers as a probe for measuring the performance of
arsine purifiers within a MetalOrganic Vapour Phase Epitaxy system. Comparisons
between two different commercially available purifiers are based on the
analysis of low temperature photoluminescence emission spectra from thick QWs,
grown on GaAs substrates misoriented slightly from (100). Neutral excitons
emitted from these structures show extremely narrow linewidths, comparable to
those which can be obtained by Molecular Beam Epitaxy in an ultra-high vacuum
environment, suggesting that purifications well below the 1ppb level are needed
to achieve high quality quantum well growth.
