  We report the use of bilayer graphene as an atomically-smooth contact for
nanoscale devices. A two-terminal Bucky ball (C60) based molecular memory is
fabricated with bilayer graphene as a contact on the polycrystalline nickel
electrode. Graphene provides an atomically-smooth covering over an otherwise
rough metal surface. The use of graphene additionally prohibits the
electromigration of nickel atoms into the C60 layer. The devices exhibit a
low-resistance state in the first sweep cycle and irreversibly switch to a high
resistance state at 0.8-1.2 V bias. The reverse sweep has a hysteresis behavior
as well. In the subsequent cycles, the devices retain the high-resistance
state, thus making it write-once read-many memory (WORM). The ratio of current
in low-resistance to high-resistance state is lying in 20-40 range for various
devices with excellent retention characteristics. Control sample without the
bilayer graphene shows random hysteresis and switching.
