Abstract
The optical properties of large InAs/GaAs quantum dots were investigated by low-temperature photoluminescence as a function of the excitation-power density. The presence of excited states was clearly detected below the saturation regime of the ground state. We analyzed the dependence of the integrated-photoluminescence intensity on the excitation-power density and the type of radiative recombination involving the electronic ground state and the excited states inside the quantum dots. We concluded that the probability to have more than one exciton by dots must be considered, and the usual equation , must be revised to correctly describe the origin of the recombination and must include other factors as scattering, relaxation time, radiative recombination rate, and others.
Highlights
During the past few years, remarkable progress has been made in the development of nano-optoelectronic devices based on quantum dots (QDs)
We concluded that the probability to have more than one exciton by dots must be considered, and the usual equation integrated photoluminescence (IPL) I0, must be revised to correctly describe the origin of the recombination and must include other factors as scattering, relaxation time, radiative recombination rate, and others
We present a study of the excited states behavior based on the measurement of the integrated PL intensity IPL as a function of the excitation power density Pexc
Summary
During the past few years, remarkable progress has been made in the development of nano-optoelectronic devices based on quantum dots (QDs). Systems based on large-size InAs/GaAs QDs, obtained by low growth rates, have been shown to be optically active in the vicinity of 1.3 and 1.5 μm [11,13]. In order to obtain optical devices with high performance, it is crucial to understand the optical processes involved in these complex nanostructures In this sense, the optical properties of InAs/GaAs QDs have been widely investigated by photoluminescence (PL) [14,15,16,17,18,19], photoluminescence excitation spectroscopy (PLE) [15, 17], and time-resolved photoluminescence (TRPL) [15, 17,20].
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