Charge storage in mesoscopic graphitic islands fabricated using AFM bias lithography

Abstract

Electrochemical oxidation and etching of highly oriented pyrolytic graphite (HOPG) hasbeen achieved using biased atomic force microscopy (AFM) lithography, allowing patternsof varying complexity to be written into the top layers of HOPG. The graphiticoxidation process and the trench geometry after writing were monitored usingintermittent contact mode AFM. Electrostatic force microscopy reveals that the isolatedmesoscopic islands formed during the AFM lithography process become positivelycharged, suggesting that they are laterally isolated from the surrounding HOPGsubstrate. The electrical transport studies of these laterally isolated finite-layergraphitic islands enable detailed characterization of electrical conduction along thec-direction and reveal an unexpected stability of the chargedstate. Utilizing conducting-atomic force microscopy, the measuredI(V) characteristics revealed significant non-linearities. Micro-Raman studies confirmthe presence of oxy functional groups formed during the lithography process.