Optical study of strain-induced GaAs quantum dots

The excitation-intensity-dependent nonlinear luminescence as well as the lu minescence of strain-induced GaAs quantum dots (SIQDs) was studied. The lum inescence spectrum of SlQDs was composed of three well-resolved transitions and each transition had a different saturation excitation intensity. The i ncrease and saturation of luminescence was more clearly seen in the nonline ar luminescence, where the saturation excitation intensities for each energ y level were demonstrated to be proportional to the degeneracies of each le vel. The nonlinear luminescence spectra were simulated by rate equations, t aking account of the relaxation rate, the recombination rate. and the state -filling effect caused by Pauli blocking. As a result of fitting. the relax ation rate was estimated to be about 30 ps.