PHOTOLUMINESCENCE AND ITS DECAY OF THE DYE POROUS-SILICON COMPOSITE SYSTEM/

Photoluminescence (PL) and its decay in the composite system of dye/po rous silicon, consisting of oxidized porous silicon (PSi) and impregna ted dyes, have been studied. We find that the PL spectra of the dyes a re similar to that of dyes in ethanol solution while being quite diffe rent from those of dye films absorbed on the surface of c-Si. The line shape of the spectra is more symmetric for impregnated dyes than that in solution. The PL decay of the impregnated dyes has been measured. The lifetime is about 100 ps for rhodamine B impregnated in as-prepare d PSi and it becomes much shorter for that in the annealed PSi layers. The influence of absorbed dyes on the PL decay of PSi has also been m easured. It shows that impregnated dyes provide new nonradiative proce sses for the deactivation of the excited PSi. (C) 1996 American Instit ute of Physics.