Two-dimensional Materials?

Graphene is one form of carbon atoms arranged in a densely packed hexagonal lattice.  It has been called a two-dimensional material due to the fact that most references are to the form of the material that is only one atom thick.  The properties of the material are, of course, significantly different from bulk graphite.  Not surprisingly, two atom thick material has different properties from one atom or three atom thick material.  As the number of atomic layers increases, the material properties become the bulk properties.  There is large amount of research that needs to be completed before we can truly understand the benefits and challenges of the material.

As with almost all novel materials, there are reports of possible dangers.  The three references at the end of this blog link to comments about work originally published from the Brown University [1] and the University of Edinburgh, UK [2, 3].  If one reads the reports, they present a scenario where it might be possible to have an adverse effect on people.  But, knowing the potential and ensuring the necessary precautions are taken should mitigate the possibility of harm.  A very sharp knife is dangerous if mishandled.  Hopefully, all of us handle them with adequate caution.

Graphene is a pure form of carbon.  There are other possibilities where other atoms are introduced into the carbon matrix and result in totally different properties.  However, having the same dimensional thickness, the concerns raised above will still apply.

Graphane has the same honeycomb structure as graphene, except hydrogen atoms are introduced into the lattice and attach themselves to the carbon. The resulting bonds between the hydrogen and carbon atoms effectively change the conducting structure of graphene to the insulating properties of graphene.  Even with this addition, graphane retains the thinness, super-strength, flexibility and density of graphene.

There are other two-dimensional materials that also have interesting properties.  Boron Nitride has seen significant research.  There is a 2012 article in IEEE Spectrum [4] that indicates Molybdenum Disulfide cold be a choice for future electronics.

Carbon Nano Tubes (CNT) are the same basic structure as graphene, but exist in a tubalar form.  Depending on the chirality (direction of roll of the carbon matrix), the material exhibits conductive or semiconducting properties.  With conductive, insolating, and semiconducting properties, the question is how soon will there be electronic applications of these materials.

The answer requires that there be a manufacturing process developed.  Current semiconductor manufacturing produces billions of transistors for single devices through a process that creates the transistors via an additive process.  Considering that millions of devices are produced each week, the number of individual transistors produced per second is very large.  Current development efforts of nanoelectronics are still very slow compared to semiconductors.  Developments in the manufacturing process are required before nanomaterial based electronics become affordable.

One parting thought for this week’s blog.  If we can change graphene (conductive) to graphene (insulating) by adding hydrogen, will this or other changes occur naturally when the device is exposed to an operating environment?  If it happens, then the properties of the device will change in a way that will not be beneficial.

  1. http://io9.com/graphene-miracle-material-could-be-toxic-to-humans-786847545
  2. http://www.materialstoday.com/view/26393/is-graphene-safe-comment/
  3. http://news.techeye.net/science/health-fears-hamper-graphene-development
  4. http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/graphene-is-losing-favor-as-the-twodimensional-material-of-the-future

Next week’s blog will consider the classification of nanomaterials based on size alone.

About Walt

I have been involved in various aspects of nanotechnology since the late 1970s. My interest in promoting nano-safety began in 2006 and produced a white paper in 2007 explaining the four pillars of nano-safety. I am a technology futurist and is currently focused on nanoelectronics, single digit nanomaterials, and 3D printing at the nanoscale. My experience includes three startups, two of which I founded, 13 years at SEMATECH, where I was a Senior Fellow of the technical staff when I left, and 12 years at General Electric with nine of them on corporate staff. I have a Ph.D. from the University of Texas at Austin, an MBA from James Madison University, and a B.S. in Physics from the Illinois Institute of Technology.

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