Concentration of Electric Field near Si Dot/Thermally-Grown SiO2 Interface

The dot-induced concentration of electric field was studied by current-voltage (I–V) measurements of metal-oxide-semiconductor (MOS) diodes containing a high density of Si dots embedded in the gate SiO2. Using a nanometer-scale local oxidation process developed by the authors, single-crystalline Si dots covered with a thermally grown SiO2 were formed on a tunnel SiO2/n +-Si substrate. I–V measurements through the gate SiO2 (∼20 nm thick) showed enhancement of the Fowler-Nordheim (FN) tunneling current in comparison with the conventional MOS diode. This phenomenon was ascribed to a strong electric field generated locally near the gate SiO2/Si dot interface, which reflects the ultrasmall curvature of the Si dot. In fact, simulation of the potential distribution provided evidence of the concentration of the electric field.