With the
Campanile probe, optical excitation and collection are spatially confined
to the
nano-sized gap at the apex of the tip, which is scanned over the sample,
recording a full
emission spectrum at each position.
Berkeley Lab Researchers Use Award-Winning Campanile Probe
on Promising Semiconductor
(August 15, 2015) Scientists
with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National
Laboratory (Berkeley Lab) have used a unique nano-optical probe to study the
effects of illumination on two-dimensional semiconductors at the molecular
level. Working at the Molecular Foundry, a DOE Office of Science User Facility,
the scientific team used the “Campanile” probe they developed to make some
surprising discoveries about molybdenum disulfide, a member of a family of semiconductors,
called “transition metal dichalcogenides (TMDCs), whose optoelectronic
properties hold great promise for future nanoelectronic and photonic devices.
“The Campanile probe’s remarkable resolution enabled us to
identify significant nanoscale optoelectronic heterogeneity in the interior
regions of monolayer crystals of molybdenum disulfide, and an unexpected,
approximately 300 nanometer wide, energetically disordered edge region,” says
James Schuck, a staff scientist with Berkeley Lab’s Materials Sciences
Division. Schuck led this study as well as the team that created the Campanile
probe, which won a prestigious R&D 100 Award in 2013 for combining the
advantages of scan/probe microscopy and optical spectroscopy.
(From left)Jim
Schuck, Wei Bao and Nicholas Borys at the Molecular Foundry
where they made
surprising discoveries about 2D MoS2, a promising TMDC
semiconductor
for future photonic and nanoelectronic devices. (Photo by Roy Kaltschmidt)
“This disordered edge region, which has never been seen
before, could be extremely important for any devices in which one wants to make
electrical contacts,” Schuck says. “It might also prove critical to
photocatalytic and nonlinear optical conversion applications.”
Comparison
between image of MoS2 flake captured with Campanile probe and
image of same
flake captured with scanning confocal microscopy
shows the
Campanile probe’s enhanced resolution.
Schuck, who directs the Imaging and Manipulation of
Nanostructures Facility at the Molecular Foundry, is the corresponding author
of a paper describing this research in Nature Communications. The paper is
titled “Visualizing nanoscale excitonic relaxation properties of disordered
edges and grain boundaries in monolayer molybdenum disulfide.” The co-lead
authors are Wei Bao and Nicholas Borys. (See below for a complete list of
authors.)