ANM
2010
3rd
International Conference on Advanced Nano Materials
12-15 September 2010 - Agadir, Morocco
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Abstract
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ANMM312 |
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STRAIN-INDUCED NANOSTRUCTURES AND NANOCHEMISTRY AT
ADVANCED SEMICONDUCTOR SURFACES AND INTERFACES |
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Patrick G. Soukiassian |
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Commissariat à l’Energie Atomique, Saclay
and Université de Paris-Sud, Orsay, France |
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Silicon
carbide (SiC) and graphene are advanced semiconductors having figures
of merit scaling well above those of well-established semiconductors.
SiC main characteristics include i) a wide band gap (2.4 to 3.3 eV
depending on the polytype), ii) biocompatibility, iii) excellent
mechanical properties, and iv) high resistance to radiation damages.
Strain/stress is the driving force in SiC surface/interface
organization leading to complex structures and massively parallel
passive/active nano-lines/nano-wires self-organizing at SiC surfaces.
Another interesting feature is to have SiC as a very suitable substrate
for epitaxial graphene growth. Graphene, a single atomic layer of
graphite, exhibits outstanding transport properties, with carriers
moving at zero mass and constant velocity just like photons, leading to
linear valence band dispersion forming Dirac cones and unprecedented
mobility up-to 250.000 cm2/V-1 at RT. Graphene
also has the highest mechanical resistance ever measured. Nano-objects
and nanochemistry at SiC and graphene surfaces and interfaces are
investigated by advanced experimental techniques. It includes scanning
tunneling microscopy/spectroscopy, synchrotron radiation-based
photoelectron spectroscopies, infrared absorption spectroscopies, and
state-of-the-art theoretical calculations. Among some important issues,
the following will be presented and discussed:
• The 1st example of H-induced semiconductor surface metallization
on a SiC surface, also taking place on a pre-oxidized surface, with an
amazing isotopic effect using D.
• Monitoring the graphene band-gap by selective oxidation or
hydrogenation
• Atomic crack defects developing at SiC surfaces
• Nano-objects forming mesas with steep sides suggestive of C
nanotubes at graphene/SiC interface, triggering interface states
possibly detrimental to carrier mobility.
• Graphene layer going deep into nano-cracks at SiC surface with
no disruption or resulting electronic interface states.
Strain appears to play a central role in these properties. These
results directly impact engineering the properties of semiconductor
surface/interface. It also allows to achieve on the same surface two
opposite functions, metallization and passivation, which is especially
interesting for interfacing with biology.
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