Researchers take first steps towards strain-based graphene engineering
August 5, 2009
Researchers at the University of California, Riverside, have reported their successful observation and controlled creation of one- and two-dimensional ripples in one-atom thick graphene sheets, in an effort that will soon lead to their exploitation for the production of high-performance nanoscale electronics.
Using graphene in place of silicon
Scientists have long known the unique properties of graphene, which presents an extremely thin and mechanically resistant honeycomb, two-dimensional atomic structure that is capable of conducting high rates of heat and electricity. These characteristics make graphene ideal for manufacturing highly resistant structures such as carbon nanotubes, as well as a number of nanoscale devices for applications in the field of electronics.
For many years, Graphene, which is simply an isolated, one-atom thick layer of graphite, has been thought capable of replacing silicon as the main semiconductor component in today's electronics. However, even though graphite has been studied for decades, only recently in 2004 were scientists able to isolate a single sheet of graphene, which means many aspects still need to be studied and understood before graphene-based chips can become a reality.
One of the main challenges is presented by the numerous ripples which form in graphene sheets whenever they are exposed to a strong change in temperature. These ripples, which form in an unpredictable way, can seriously degrade the properties of its atomic structure and make the performance of a graphene sheet subject to a great deal of chance.
But controlling the formation of ripples could also be beneficial because, scientists believe, they could open up a new field of research and be used in nanoscale devices (strain-based devices). For instance, the ripples could be used to produce magnetic fields that steer and otherwise manipulate electrons in nanoscale devices without the need for an external magnet.
The road towards strain-based graphene electronics
Using a conceptually simple thermal manipulation, the researchers were able to observe the ripples and produce them controlling their orientation, as well as their amplitude and wavelength. Using a scanning electron microscope (SEM) with a built-in heater, the team was able to witness the strains form in graphene and elaborate a model for how these evolve.
Chun Ning (Jeanie) Lau, an associate professor of physics who led the research efforts, commented: "Our ability to control and manipulate the ripples in graphene sheets represents the first step towards strain-based graphene engineering. We show that suspended graphene is almost invariably rippled, and this may need to be considered in the interpretation of a broad array of existing and future research."
The results of the study have appeared in the July 26 online edition of Nature Technology.