Damage reduction of plasma-treated carbon surfaces by controlled plasma

A glassy carbon (GC) plate was treated with RF glow discharged argon (Ar) plasma in a vacuum chamber with two parallel-plate electrodes. The sheath voltage was controlled independently of other plasma parameters by means of a shunting circuit which was connected parallel to the electrodes. After 30 s of treatment without the shunting circuit, the contact angle of water on the GC surface decreased from 90° to 0°, and the half band width of the Raman band at 1360 cm -1 on the GC surface increased from 65 cm -1 to 85 cm -1 due to a disordered structure in carbon. When sheath voltage was kept constant at 80 V by means of the shunting circuit, the contact angle and the half band width changed to 0° and 72 cm -1 respectively, with a high ion density of 6×10 10 cm -3 . GC surfaces were modified sufficiently in a short time and protected from damage using a high-density of ions having moderate collision energy in controlled plasma.