Nanoprobe photoluminescence of quasi-zero-dimensional InGaAsP quantum dots

The nanoprobe photoluminescence (PL) of InGaAsP dots with quasi-zero-dimensional (quasi-0D) confinement has been studied by using a scanning near-field optical microscope. The quasi-0D InGaAsP quantum dots (QDs) with various degrees of 0D/2D confinement were prepared using an in situ phosphidation technique developed by us to modify the conventional InGaAs QDs in order to partly flatten InGaAsP quasi-0D QDs. The fine peaks originating from the 0D confinement of QDs converged into a quantum-well peak with an increase in phosphidation time. The bias effects on the nanoprobe PL spectrum revealed that the photocarriers in the quasi-0D structures are mobile in the 2D layer coexisting with 0D potentials of the QDs.