The influence of double-layer charge interaction on charge injection and charge decay in Si nanocrystals

The charge injection and decaying processes along the vertical direction in single-layer and double-layer Si nanocrystals embedded in a SiO2 matrix are investigated by electrostatic force microscopy. The charges trapped in the double-layer Si nanocrystals are found to decay much more slowly than those trapped in the single-layer sample. This phenomenon indicates that the double-layer structure of a Si nanocrystal sample can retard the charge decay process remarkably. We suggest that the Coulomb repulsive interaction of the charges trapped in one Si nanocrystal layer with those trapped in another Si nanocrystal layer is responsible for the blocking of the charge decay along the vertical direction of the structure.