Luminescence Characteristics of InGaAs/GaAs Quantum Dots Emitting Near 1.5 μm

Long-wavelength emission near 1.5 mu m at room temperature has been achieved from InGaAs/GaAs quantum dots (QDs) and the luminescence characteristics of the QDs have been analyzed. The PL peaks originating from excited states LIP to the 4th excited state are always seen under PL excitation powers that vary by a factor of 100. The intensities of all these quantized energy state peaks increase continuously with increasing PL excitation power. To the contrary, the PL Peak energies do not change much while the peak intensity changes by more than tenfold. All these characteristics are shown to be caused by the carrier distribution among the quantized energy states far from quasi-equilibrium in the conduction and the valence bands. This non-equilibrium carrier population is explained to be clue to the difficulty in carrier transfer among QDs while the number of carriers in the QDs is not uniform due to the spatially non-uniform QD density and non-uniform PL excitation Power density.