External quantum efficiency of single porous silicon nanoparticles

We use a combination of single nanoparticle luminescence and scanning force microscopy to determine the quantum efficiency (QE) of single porous Si na noparticles and to determine the ratio of luminescent nanoparticles deposit ed on a silica surface to the total nanoparticles. An estimate of the QE of bulk porous Si based on these data compares favorably to the QE measured e xperimentally. From this we conclude that the 1% QE of bulk porous Si measu red experimentally results primarily from a statistical distribution of hig h QE quantum-confined Si chromophores. (C) 1999 American Institute of Physi cs. [S0003-6951(99)03314-8].