Photoluminescence of InGaAs(P) dots with quasi-zero-dimensional confinement

Photoluminescence (PL) of InGaAs(P) dots with quasi zero-dimensional (0D) confinement has been measured and discussed from the viewpoint of dot composition/shape, energetic/spatial confinement, and the coexistence of 0D/2D in the same layer. Quasi-0D confinement structures were prepared by the self-assembly of InGaAs dots on GaAs and their in situ phosphidation, which changes the dot composition and shape at the same time. From the temperature dependence of photoluminescence versus phosphidation time, it was found that PL peak energy and quenching temperature for various quasi-0D confinements are dominated by the dot composition rather than the dot shape, whereas the diamagnetic shift is affected by the dot shape as well. The series of near-field PL spectra is presented for the structures with OD/2D transition, where dot coupling proceeds. Fine PL peaks of 0D confinement in the near-field PL spectrum shift toward higher energies and coalesce into one quantum well (QW) peak according to phosphidation, but the width of each fine peak remains unchanged. Coexistence of 0D and 2D confinement in the same layer has been proved by fine 0D peaks superimposed on a QW peak. Since the photon energies are close among coexisting 0D and 2D peaks, the dot-to-dot electron interaction must be weak even in these quasi-0D systems.