Effect of the insertion of an ultrathin AlP layer on the optical properties of GaAsP/GaP quantum wells

We have systematically investigated the correlation between electronic stat es and optical properties in indirect GaAsP/GaP quantum wells (QW's) which have an ultrathin A1P layer inserted during fabrication. The insertion of 1 monolayer (ML) of A1P at the center of a 60-Angstrom GaAsP QW drastically increased the photoluminescene intensity, and in particular the efficiency of the no-phonon (NP) transition. The NP intensity relative to its TO phono n replica was found to be greatly dependent on the structural parameters an d was drastically reduced when the arsenic composition of the well region e xceeded 15%. The relative NP intensity was found to increase sharply as the width of the AIP layer was increased above 2 ML's. These results suggest t hat the efficiency of the NP transition is improved when the X-z electrons are involved in radiative recombination rather than the X-xy electrons.