Ultrasmall, uniform-size (∼1 nm) Si nanoparticles, dispersed from p-type boron-doped silicon, are reconstituted on a Si substrate. Electronic transport processes are studied by current–voltage spectroscopy at room temperature, using scanning tunneling microscopy, in a two-terminal configuration, under both dark conditions and light illumination. Unlike the dark conditions, we observe, under light irradiation, for negative tip biasing, a regular structure at ∼1.0 eV period. The series is discussed in terms of light-induced hole states that otherwise are highly infrequent in ultrasmall Si particles, under standard low doping. © 2000 American Institute of Physics.