Charge injection in individual silicon nanoparticles deposited on a conductive substrate

We report on charge injection in individual silicon nanoparticles deposited on conductive substrates. Charges are injected using a metal-plated atomic force microscope tip, and detected by electric force microscopy (EFM). Due to the screening efficiency of the conductive substrate, up to ∼200 positive or negative charges can be stored at moderate (<10 V) tip–substrate injection voltage in ∼40 nm high nanoparticles, with discharging time constants of a few minutes. We propose an analytical model in the plane-capacitor approximation to estimate the nanoparticle charge from EFM data. It falls in quantitative agreement with numerical calculations using realistic tip/nanoparticle/substrate geometries.