Figure 1

μPL spectra from the investigated InGaAs/GaAs QD embedded in a mesa of 1.3 μm diameter at 5 K. X—exciton, X⁺—positive trion, X⁻—negative trion, XX—biexciton. (a) Spectra for different excitation powers in the range of (0.05–10) \(\upmu{\mathrm{W}}\). (b) Double logarithmic plot of the µPL intensity as a function of excitation power. Symbols denote the measured data points, the solid lines represent I ∝ P^α dependence with a near quadratic (1.95) and linear (1.08) behavior for biexciton and exciton, respectively. Positive and negative trions exhibit superlinear dependence (1.17 and 1.50, respectively). (c) Polarization-resolved µPL spectra for perpendicular polarization angles for X in the left panel and polarization dependence of emission energy for X and XX in the right panel, both indicating exciton fine structure splitting of \({\Delta }_{FSS}=67\, \upmu {\mathrm{eV}}\).