LASER IRRADIATION OF GAAS-GAALAS MULTIQUANTUM-WELL STRUCTURE

We have studied the effects produced by laser irradiation with 355 nm photons on a heterostructure made of three independent GaAs/Ga0.67Al0. 33As quantum wells. By comparing the luminescence of the three quantum wells before and after the laser irradiation for different durations and fluence values one could determine if the structure of each quantu m well has been altered or not. Then we achieved complementary observa tions of the irradiated multi-quantum wells structures, using both sca nning and transmission electron microscopy. We came to the conclusion that the alteration of the multi-quantum wells structure results from two main consequences of the sample pulsed laser heating: the formatio n of an altered layer which accompanies the pulsed laser sputtering pr ocess and the thermal diffusion process. (C) 1997 Elsevier Science B.V .