The graphene layer was prepared by keeping the Ru crystal at 1150 K in UHV while exposing it to an ethylene partial pressure of 1 × 10−7 mbar for 3 min. Acetonitrile was introduced in the UHV chamber via a leak valve to produce a partial pressure of 1 × 10−6 torr during 12 min with the sample held at 374 K. TCNQ molecules were evaporated from a quartz crucible heated at 350 K with the sample held at room temperature with a deposition rate of one layer every 4 min.