Charging effect in silicon nanocrystals observed by electrostatic and Kelvin-probe force microscopy

Si nanocrystals (Si-NCs) sandwiched by amorphous silicon carbide (a-SiC) were fabricated using KrF excimer laser crystallization technique. Charge injection into Si-NCs in a microscopic area was realized in an atomic force microscopy (AFM) system and the charging effect was subsequently studied in situ by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM). Numerical calculations based on electric field analysis in both EFM and KPFM measurements were carried out to extract the areal charge densities and the results are compatible with each other. Finally, the advantages and disadvantages of the two scanning probe techniques are discussed.