In this work, the n-type FET chips were fabricated by Toppan Co.,Ltd. (Japan).Each FET chip consist of two gate electrodes in which the gate oxide surface is SiO2 layer on the Si substrate with a size of 1000 m in width and 10 m in length. All electrical measurements were performed using a digital source meter (Keithley 2612). X-rayphotoelectron spectroscopy (XPS) analysis was carried out for the specimens prepared not on FET chip but on Si wafer with SiO2 layer using a micro XPS instrument (PHI-5000 Versa Probe WS, ULVAC-PHI Inc.) with monochromatic Al K X-ray source.