Effects of thermal annealing procedure and a strained intermediate layer on a highly-strained GaInNAs/GaAs double-quantum-well structure

We investigated the effects of a thermal annealing procedure and a strained intermediate layer on a highly-strained GaInNAs/GaAs double-quantum-well (DQW) structure grown by chemical beam epitaxy (CBE). To improve the crystal quality of the DQW structure, we have developed a layer-by-layer annealing procedure. in which thermal annealing is done just after the crystal growth of each GaInNAs well layer. This new annealing procedure can suppress the strain relaxation in the GaInNAs well layer and provide a DQW with both a narrow peak and high intensity in the photoluminescence spectrum. The dependence of the PL characteristics of the DQW on the strain of the intermediate layers is similar to that found in conventional III-V semiconductor material systems. The applicable range of strain was found to be from 0 to + 1.5% when GaInNAs with a strain of + 1.9% was used as the well layer. These findings should be helpful for lower-threshold operation of GaInNAs/GaAs DQW laser diodes. (C) 2000 Elsevier Science B.V. All rights reserved.