QUANTUM-SIZE EFFECTS ON RADIATIVE LIFETIMES AND RELAXATION OF EXCITONS IN SEMICONDUCTOR NANOSTRUCTURES

A systematic study of exciton dynamics is presented in quantum boxes f ormed naturally along the axis of a V-shaped quantum wire, by means of time and spatially resolved resonant photoluminescence. The dependenc e of radiative Lifetimes and relaxation mechanisms of excitons is dete rmined versus the size of the boxes. The radiative recombination rate varies linearly with the length of the box, showing that the exciton h as a coherence volume equal to the volume of the box. In a low excitat ion regime, emission from excited states has not been observed, which would be a consequence of relaxation bottleneck, but there is clear ev idence that relaxation via emission of LBL phonons depends strongly on the energy separation between the different quantum box levels. [S016 3-1829(98)07839-4].