C – V characteristics and DLTS spectra of heterostructures made up of layers of closely packed amorphous Si nanoparticles deposited by laser electrodispersion onto single-crystal p -Si substrates have been examined. The patterns observed in the behavior of the C – V characteristics and DLTS spectra measured in the dark and under illumination with white light at various bias pulse voltages U _ b and filling pulse voltages U _ f suggest that the spatially localized amorphous Si nanoparticles have an average size of less than 2 nm, which is comparable with the de Broglie electron wavelength, and are characterized by quantum confinement. The ground and excited states of quantum dots are formed and exhibit the Stark effect and effects of electricdipole and controllable metastable occupancy under illumination.