Removal of charging on SiO2/Si structure during photoelectron spectroscopy measurements by metal overlayer

Since the density of charges resulting from photoemission on SiO2 strongly depends on the leakage characteristic, the magnitude of the shift of the SiO2 Si 2p peak from the substrate Si 2p peak becomes higher with a decrease in the leakage current density. The SiO2 layer formed with 98 wt% HNO3 aqueous solutions possesses a lower leakage current density than that fabricated with 40 wt% HNO3 solutions, resulting in the higher shift of the SiO2 Si 2p peak. The lower leakage current density results from a higher atomic density of the SiO2 layer and a lower density of suboxide species.