SiO2 and Cu substrates
with native oxides were prepared by Intel Co. Electron-beam evaporation
was performed to deposit 7.7 ± 0.1 nm thick Cu films onto SiO2 substrates. For patterning, 400 mesh TEM grids (Ted Pella,
Inc., USA) were used as deposition masks. Cu was evaporated in a vacuum
with a base pressure below 4 × 10–6 Torr (Scheme S1 ). All substrates were precleaned by
0.5 wt % potassium hydroxide (KOH) solution at room temperature for
5 min and then sonicated by 70% ethanol solution (Fisher Scientific,
USA) and DI water for 10 min.
with native oxides were prepared by Intel Co. Electron-beam evaporation
was performed to deposit 7.7 ± 0.1 nm thick Cu films onto SiO2 substrates. For patterning, 400 mesh TEM grids (Ted Pella,
Inc., USA) were used as deposition masks. Cu was evaporated in a vacuum
with a base pressure below 4 × 10–6 Torr (
0.5 wt % potassium hydroxide (KOH) solution at room temperature for
5 min and then sonicated by 70% ethanol solution (Fisher Scientific,
USA) and DI water for 10 min.