Editor’s note: This
article is by IBM Research Staff Member and Master Inventor Dr. Jeehwan Kim
Graphene holds incredible promise as a linchpin material for
breakthroughs in numerous technologies, and my team at IBM’s Thomas J. Watson
Research Center is working to make its potential a reality. Due to its
incredible strength and supreme electrical, optical and mechanical properties, graphene
– pure carbon functional at the thickness of one atom – has been touted as the
next big thing in everything from high-frequency transistors and
photo-detectors, to flexible electronics and biosensors.
IBM is investing $3B over the next five years towards initiatives such as this, which are building a
bridge to a “post-silicon” era.
Part of what makes the material so promising is its strength
relative to thickness. At only .3 to .4 nanometers thick (that’s 60,000 times
thinner than a sheet of plastic wrap, or 1,000,000 times thinner than a strand
of human hair), graphene is an astonishing 200 times stronger than steel. It is
also the world’s most conductive material yet discovered, extraordinarily
flexible and – as a single layer of carbon atoms – the first two-dimensional
material.
Our groundbreaking approach, known as “graphene-based
growth/transfer,” allows single-crystalline semiconductor film growth on
graphene – rather than on expensive, single-crystalline wafers. The graphene
serves as a “seed” for single-crystalline film growth, and because this film
can be separated precisely from the graphene surface, the graphene can be
reused for further growth. In principle, graphene has therefore been
demonstrated as an infinitive source for growing these semiconductor materials,
making the work an enormously cost-effective and reliable production method for
single-crystalline films.
Graphene’s periodic hexagonal crystal structure then allowed
us to experiment with growing other semiconductor materials that demonstrate
similar structural properties. Previously, production of single-crystalline
semiconductor films required the use of ~1 millimeter-thick, single-crystalline
wafer templates that were not reusable and were very expensive. For example,
growth of a 4-inch, wafer-scale GaN (gallium nitride, a direct bandgap
semiconductor) film would require a 4-inch SiC wafer – at the cost of some
$3000. Now, graphene can be produced in a lab to replace the expensive SiC
wafer.
Furthermore, the new growth technique is useful in that
semiconductor devices can be deposited on graphene and released or transferred
to a flexible substrate.
While we have demonstrated an important, present-day use for
this material, the future of graphene as a standalone material is still bright.
Uses for graphene are being developed for a number of electronics, and over the
next five years, the material could be used as transparent electrodes for touch
screen devices, rollable e-paper and foldable LEDs. In the near future, uses
are being developed for large-area graphene in high-frequency transistors,
logic transistors/thin-film transistors and beyond. Its high electronic mobility
– the ability of charged particles to move through a medium in response to an
electronic field – makes graphene a promising material.
Read Principle of direct van der Waals epitaxy of single-crystalline films on epitaxial graphene by Jeehwan Kim, Can Bayram, Hongsik Park, Cheng-Wei
Cheng, Christos Dimitrakopoulos, John A. Ott, Kathleen B. Reuter, Stephen W.
Bedell and Devendra K. Sadana Labels: graphene, nature communications, semiconductor, silicon