Walter de Heer
Encyclopedia
Walter Alexander "Walt" de Heer is a Dutch physicist and nanoscience researcher known for discoveries in the electronic shell structure of metal clusters, magnetism in transition metal
clusters, field emission
and ballistic conduction
in carbon nanotube
s, and graphene
-based electronics.
from the University of California, Berkeley
in 1986 under the supervision of Walter D. Knight
. He worked at the École Polytechnique Fédérale de Lausanne
in Switzerland
from 1987 to 1997, and is currently a Regents' Professor of Physics at the Georgia Institute of Technology
. He directs the Epitaxial Graphene Laboratory in the School of Physics and leads the Epitaxial Graphene Interdisciplinary Research Group at the Georgia Tech Materials Research Science and Engineering Center
.
metal clusters that demonstrated the electronic shell structure of metal clusters. This is a property of small metal clusters composed of few atoms that develop atom-like electronic properties (these clusters are also referred to as superatom
s). In Switzerland, he developed methods of measuring the magnetic properties of cold metal clusters and described how magnetism
develops in these clusters as their size increases from atomic to bulk. He is the author of the most highly-cited review articles on metallic clusters.
De Heer turned to carbon nanotube
s in 1995, showing that they are excellent field emitters, with potential application to flat panel display
s. In 1998, he discovered that carbon nanotubes are ballistic conductors
at room temperature, meaning that they conduct electrons over relatively large distances without resistance. This is a key selling point of nanotube- and graphene-based electronics.
His nanotube work led to consideration of the properties of "opened" carbon nanotubes and the development of graphene
-based electronics, starting in 2001. Anticipating that patterned graphene structures would behave like interconnected carbon nanotubes, he proposed several avenues of graphene preparation, including exfoliation of graphite flakes to oxidized silicon wafers and epitaxial growth on silicon carbide
. The latter was deemed most promising for large-scale integrated electronics
, and was funded by Intel Corporation
in 2003. In 2004, the group was awarded additional funding from the National Science Foundation
for the pursuit of graphene science. The first paper, "Two dimensional electron gas properties of ultrathin epitaxial graphite", was presented in March 2004 at a meeting of the American Physical Society
and published in December under the title, "Ultrathin epitaxial graphite: Two dimensional electron gas properties and a route towards graphene based electronics". This paper, based primarily on data documented in 2003, describes the first electrical measurements of epitaxial graphene, reports fabrication of the first graphene transistor
, and outlines the desirable properties of graphene for use in graphene-based electronics. De Heer and coworkers Claire Berger and Phillip First hold the first patent on graphene-based electronics, provisionally filed in June 2003. The approach championed by de Heer has the advantage of producing graphene directly on a high-quality electronic material (silicon carbide) and does not require isolation or transfer to any other substrate.
Faculty Awards in 2007 and 2008, and his work on graphene transistors was named as one of Technology Review
's 10 emerging technologies "most likely to change the way we live" in 2008. In September 2009, de Heer was awarded the ACSIN Nanoscience Prize "for his visionary work in developing the field of graphene nanoscience and technology". De Heer has been awarded the 2010 Materials Research Society Medal "for his pioneering contributions to the science and technology of epitaxial graphene". His h-index
is currently 53.
Transition metal
The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...
clusters, field emission
Field emission
Field emission is emission of electrons induced by an electrostatic field. The most common context is FE from a solid surface into vacuum. However, FE can take place from solid or liquid surfaces, into vacuum, air, a fluid, or any non-conducting or weakly-conducting dielectric...
and ballistic conduction
Ballistic conduction
Ballistic conduction is the unimpeded flow of charge or energy carrying particles over relatively long distances in a material. Normally, transport of electrons is dominated by scattering events, which relax the carrier momentum in an effort to bring the conducting material to equilibrium...
in carbon nanotube
Carbon nanotube
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...
s, and graphene
Graphene
Graphene is an allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm, who described single-layer...
-based electronics.
Academic career
De Heer earned a doctoral degree in PhysicsPhysics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
from the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
in 1986 under the supervision of Walter D. Knight
Knight shift
The Knight shift is a shift in the nuclear magnetic resonance frequency of a paramagneticsubstance first published in 1949 by the American physicist Walter David Knight.The Knight shift is due to the conduction electrons in metals...
. He worked at the École Polytechnique Fédérale de Lausanne
École polytechnique fédérale de Lausanne
The École polytechnique fédérale de Lausanne is one of the two Swiss Federal Institutes of Technology and is located in Lausanne, Switzerland.The school was founded by the Swiss Federal Government with the stated mission to:...
in Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
from 1987 to 1997, and is currently a Regents' Professor of Physics at the Georgia Institute of Technology
Georgia Institute of Technology
The Georgia Institute of Technology is a public research university in Atlanta, Georgia, in the United States...
. He directs the Epitaxial Graphene Laboratory in the School of Physics and leads the Epitaxial Graphene Interdisciplinary Research Group at the Georgia Tech Materials Research Science and Engineering Center
Materials Research Science and Engineering Centers
MRSEC is an acronym for Materials Research Science and Engineering Centers, funded by the United States National Science Foundation.Materials Research Science and Engineering Centers support interdisciplinary and multidisciplinary materials research and education of the highest quality while...
.
Research
De Heer and his research groups have made significant contributions to several important areas in nanoscopic physics. As a graduate student at UC-Berkeley, he participated in groundbreaking research on alkaliAlkali metal
The alkali metals are a series of chemical elements in the periodic table. In the modern IUPAC nomenclature, the alkali metals comprise the group 1 elements, along with hydrogen. The alkali metals are lithium , sodium , potassium , rubidium , caesium , and francium...
metal clusters that demonstrated the electronic shell structure of metal clusters. This is a property of small metal clusters composed of few atoms that develop atom-like electronic properties (these clusters are also referred to as superatom
Superatom
Superatoms are clusters of atoms that seem to exhibit some of the properties of elemental atoms.Sodium atoms, when cooled from vapor, naturally condense into clusters, preferentially containing a magic number of atoms . The first two of these can be recognized as the numbers of electrons needed to...
s). In Switzerland, he developed methods of measuring the magnetic properties of cold metal clusters and described how magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
develops in these clusters as their size increases from atomic to bulk. He is the author of the most highly-cited review articles on metallic clusters.
De Heer turned to carbon nanotube
Carbon nanotube
Carbon nanotubes are allotropes of carbon with a cylindrical nanostructure. Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1, significantly larger than for any other material...
s in 1995, showing that they are excellent field emitters, with potential application to flat panel display
Flat panel display
Flat panel displays encompass a growing number of electronic visual display technologies. They are far lighter and thinner than traditional television sets and video displays that use cathode ray tubes , and are usually less than thick...
s. In 1998, he discovered that carbon nanotubes are ballistic conductors
Ballistic conduction
Ballistic conduction is the unimpeded flow of charge or energy carrying particles over relatively long distances in a material. Normally, transport of electrons is dominated by scattering events, which relax the carrier momentum in an effort to bring the conducting material to equilibrium...
at room temperature, meaning that they conduct electrons over relatively large distances without resistance. This is a key selling point of nanotube- and graphene-based electronics.
His nanotube work led to consideration of the properties of "opened" carbon nanotubes and the development of graphene
Graphene
Graphene is an allotrope of carbon, whose structure is one-atom-thick planar sheets of sp2-bonded carbon atoms that are densely packed in a honeycomb crystal lattice. The term graphene was coined as a combination of graphite and the suffix -ene by Hanns-Peter Boehm, who described single-layer...
-based electronics, starting in 2001. Anticipating that patterned graphene structures would behave like interconnected carbon nanotubes, he proposed several avenues of graphene preparation, including exfoliation of graphite flakes to oxidized silicon wafers and epitaxial growth on silicon carbide
Silicon carbide
Silicon carbide , also known as carborundum, is a compound of silicon and carbon with chemical formula SiC. It occurs in nature as the extremely rare mineral moissanite. Silicon carbide powder has been mass-produced since 1893 for use as an abrasive...
. The latter was deemed most promising for large-scale integrated electronics
Integrated circuit
An integrated circuit or monolithic integrated circuit is an electronic circuit manufactured by the patterned diffusion of trace elements into the surface of a thin substrate of semiconductor material...
, and was funded by Intel Corporation
Intel Corporation
Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...
in 2003. In 2004, the group was awarded additional funding from the National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...
for the pursuit of graphene science. The first paper, "Two dimensional electron gas properties of ultrathin epitaxial graphite", was presented in March 2004 at a meeting of the American Physical Society
American Physical Society
The American Physical Society is the world's second largest organization of physicists, behind the Deutsche Physikalische Gesellschaft. The Society publishes more than a dozen scientific journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than 20...
and published in December under the title, "Ultrathin epitaxial graphite: Two dimensional electron gas properties and a route towards graphene based electronics". This paper, based primarily on data documented in 2003, describes the first electrical measurements of epitaxial graphene, reports fabrication of the first graphene transistor
Transistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
, and outlines the desirable properties of graphene for use in graphene-based electronics. De Heer and coworkers Claire Berger and Phillip First hold the first patent on graphene-based electronics, provisionally filed in June 2003. The approach championed by de Heer has the advantage of producing graphene directly on a high-quality electronic material (silicon carbide) and does not require isolation or transfer to any other substrate.
Honors and awards
In 2006, de Heer was named as one of the "Scientific American 50", a list of individuals/organizations honored for their contributions to science and society during the preceding year. In 2007, he and his research group were awarded the prestigious W.M. Keck Foundation grant for continuation of work on "nanopatterned epitaxial graphene electronic devices that work at room temperature." De Heer received IBMIBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
Faculty Awards in 2007 and 2008, and his work on graphene transistors was named as one of Technology Review
Technology Review
Technology Review is a magazine published by the Massachusetts Institute of Technology. It was founded in 1899 as "The Technology Review", and was re-launched without the "The" in its name on April 23, 1998 under then publisher R. Bruce Journey...
's 10 emerging technologies "most likely to change the way we live" in 2008. In September 2009, de Heer was awarded the ACSIN Nanoscience Prize "for his visionary work in developing the field of graphene nanoscience and technology". De Heer has been awarded the 2010 Materials Research Society Medal "for his pioneering contributions to the science and technology of epitaxial graphene". His h-index
H-index
The h-index is an index that attempts to measure both the productivity and impact of the published work of a scientist or scholar. The index is based on the set of the scientist's most cited papers and the number of citations that they have received in other publications...
is currently 53.