ABSTRACT
Direct growth of semiconductor quantum dot structures can now be achieved in standard growth systems by using lattice mismatch induced three dimensional growth. Here we present the optical properties of heterodots which are formed by selective growth of a thin InGaAs layer on top of nanoscale InP islands. The photoluminescence spectrum from these InGaAs heterodots exhibits a peak at 1.387 eV with a full width at half maximum of 12 meV. The photoluminescence excitation spectrum of the heterodots exhibits an absorption edge at 1.394 eV of relatively small intensity indicating that the oscillator strength of the electron - hole pair confined in the InGaAs heterodots is weak. However, time-resolved photoluminescence spectra exhibit very efficient relaxation processes from the wetting layer and from the surrounding GaAs to the InGaAs layer. Finally, recombination paths occurring in this system are identified according to a proposed schematic band diagram.
