A little zinc can do a lot of damage to graphene. Rice Univ.
researchers have taken advantage of that to create single-atomic-layer
The Rice lab of chemist James Tour reported in Science that sputtering zinc onto multilayered graphene enabled the
team to remove a single layer at a time without disturbing the layers beneath.
The discovery could be useful as researchers explore graphene’s electrical
properties for new generations of microcircuitry and other graphene-based
The researchers created a graphene checkerboard by removing horizontal and
vertical layers to create a three-dimensional pattern.
They also printed a micro owl, Rice’s mascot, about 15 millionths of a meter
“The removal of a single sheet of graphene or graphene oxide was a
surprise,” said Tour, Rice’s T.T. and W.F. Chao Chair in Chemistry as well
as a professor of mechanical engineering, materials science, and computer
science. “We thought multiple layers would be removed by this protocol,
but to see single layers removed is one of those exciting events in science
where nature gives us far more than we expected.”
Tour said the ability to remove single layers of graphene in a controlled
manner “affords the most precise level of device-patterning ever known, or
ever to be known, where we have single-atom resolution in the vertical
dimension. This will forever be the limit of vertical patterning—we have hit
the bottom of the scale.”
Ayrat Dimiev, a postdoctoral scientist in Tour’s lab, discovered the
technique and figured out why graphene is so amenable to patterning. He
sputtered zinc onto graphene oxide and other variants created through chemical
conversion, chemical vapor deposition and micromechanically (the
“Scotch-tape” method). Bathing the graphene in dilute hydrochloric acid
removed graphene wherever the zinc touched it, leaving the layers underneath
intact. The graphene was then rinsed with water and dried in a stream of
For the owl, Dimiev cut a stencil in PMMA with an electron beam and placed
it on graphene oxide. He sputter-coated zinc through the stencil and then
washed the zinc away with dilute hydrochloric acid, leaving the embedded owl
Sputter-coating graphene with aluminum showed similar effects. But when
Dimiev tried applying zinc via thermal evaporation, the graphene stayed intact.
Investigation of the sputtered surface before applying the acid wash
revealed that the metals formed defects in the graphene, breaking bonds with
the surrounding sheet like a cutter through chicken wire. Sputtering zinc,
aluminum, gold and copper all produced similar effects, though zinc was best at
delivering the desired patterning.
The researchers were able to create a 100 nm line in a sheet of graphene,
which suggests the only horizontal limit to the resolution of the process is
the resolution of the metal patterning method.
“The next step will be to control the horizontal patterning with
similar precision to what we have attained in the vertical dimension,”
Tour said. “Then there’s no more room at the bottom at any dimension, at
least if we call single atoms our endpoint—which it is, for practical