Optimization of oxygen plasma based etching of single layered graphene through Raman and FESEM characterization

Post-synthesis patterning of single layered graphene (SLG) is essential to realize graphene based novel devices and sensors in practical applications. In this paper, oxygen plasma etching experiments over as grown SLG were carried out, which confirmed the complete etching of SLG layer in 240 s. SLG was grown over copper (Cu) foil by chemical vapor deposition (CVO) technique using methane (CH₄) as precursor gas and hydrogen (H₂) as carrier gas in a furnace heated to 1000 DC. To transfer SLG on SiO₂/Si substrate, PMMA was spin coated over the Cu-SLG film at 4000 rpm for 60 s, followed by etching of underlying Cu layer by dissolving it into FeCb solution. The SiO₂/Si wafer was used to fish out the free flowing PMMA coated SLG from the FeCl₃ solution, followed by thorough washing with DI water and ethanol. Acetone was used to remove the PMMA completely from the top; resulting in transferred SLG over SiO₂ surface. Etching experiments of SLG were carried out using oxygen plasma for 30 s, 90 s, 120 s, 150 s, and 240 s at 200 W RF (13.56 MHz) power, 0.8 torr pressure, and with 2-3 seem oxygen flow. Raman spectra at different etching times confirm that the 20 peak almost disappear after 240 s of etching