Second harmonic generation in stepped InAsGaAs/GaAs quantum wells

A systematic study in stepped quantum wells of InxGa1-xAs/InyGa1-yAs/GaAs(001) with indium concentration x = 14.9% and y = 6.5% and thicknesses in the range of quasi-two-dimensional behavior of Wannier excitons is performed. Experimental optical spectra are compared with model calculations. For well widths in the range of the pseudo-two-dimensional transition, where the oscillator strength of the exciton odd states is maximized, a large second harmonic generation signal is experimentally observed.