Optical study of strain-induced GaAs quantum dots

The excitation-intensity-dependent nonlinear luminescence as well as the luminescence of strain-induced GaAs quantum dots (SIQDs) was studied. The luminescence spectrum of SlQDs was composed of three well-resolved transitions and each transition had a different saturation excitation intensity. The increase and saturation of luminescence was more clearly seen in the nonlinear luminescence, where the saturation excitation intensities for each energy level were demonstrated to be proportional to the degeneracies of each level. The nonlinear luminescence spectra were simulated by rate equations, taking account of the relaxation rate, the recombination rate. and the state-filling effect caused by Pauli blocking. As a result of fitting. the relaxation rate was estimated to be about 30 ps.