Categories: News Date: May 9, 2010 Title: Nanosphere lithography for fabrication of ultranarrow graphene nanoribbons and â€œon-chipâ€ band-gap tuning of graphene
Lei Liu, Yingli Zhang , Wenlong Wang, * Changzhi Gu , Xuedong Bai, and Enge Wang*
With the rise of graphene research since 2004, the past few years have witnessed rapid progreess in exploiting graphene as an electronic material that shows great promise for future nano-electronic devices. Particular interest in this regard stems from the remarkable electronic properties of graphene, ranging from the extremely high mobility to the tunable carrier type and density. However, the fact that graphene is a zero-bandgap semimetal poses a major problem for its practical applications in making high-performance ï¬eld-effect transistors (FETs). As to how an energy gap can be induced in graphene, a known paradigm is to fabricate 1D ultranarrow graphene nanoribbons (GNRs) in which the lateral conï¬nement of charge carriers cre-ates an energy gap near the charge neutrality point. Experi-mentally, ultranarrow GNRs were ï¬rst fabricated by standard electron beam lithography (EBL) patterning in combination with reactive O 2 plasma etching of graphene sheets; how-ever EBL is known to be limited by its serial processing nature, low throughput, and high cost. Later on, the chemically derived GNRs produced via a solution processing route were reported as an alternative, but the synthetic yield was quite low. More recently, some other strategies, e.g., the longitudinal unzip-ping of carbon nanotubes, the inorganic nanowire, and diblock copolymer templated etching of graphene sheets, have also been proposed and demonstrated. Despite these important advances, an increasing demand for rapid, massively parallel, high-throughput, and low-cost fabrication strategies for ultranarrow GNRs continues to motivate research.