“Multiscale Modeling Study of Graphene Oxides”
Kyeongjae (KJ) Cho, UT Dallas
Thursday, Feb. 17, 2011
10:45 a.m., NSERL 3.204
Abstract
Graphene has been seriously considered for nanoelectronic devices because of its high
electrical mobility, high thermal conductivity and other promising material properties. In
any practical electronic device systems, electron transporting materials (silicon or
graphene) need to be controlled by insulating materials (SiO2 or graphene oxide), which
can function as gate dielectrics or a separator between device structures. Thus the role
of graphene oxide (GO) in graphene-based nanoelectronics is comparable to that of
SiO2 in silicon-based microelectronics. Consequently the graphene electronic research
community is investigating diverse oxides (e.g., GO and alumina grown on graphene
using ALD) as candidates for gate oxides. However, the atomic and electronic structures
of GO and their impact on electrical properties have not been fully understood. In this
talk we will discuss the quantitative nature of the chemical and physical properties of GO
based on atomistic and quantum simulations in close collaboration with experimental
groups. Our early modeling study has shown that graphene basal plane is relative inert.
Nevertheless, ozone was suggested to activate the basal plane for subsequent chemical
reactions, and a detailed modeling study has confirmed the epoxide forming reaction of
ozone treatment. Basal plane oxide of graphene is known to etch carbon atoms by CO
and CO2 gas species, and etch holes are formed in the carbon planes of GO structures.
The graphene edge oxide species are predicted to have metallic properties, and recent
IR experiments have demonstrated the presence of free electrons at the oxide edges of
reduced GO. Furthermore, edge oxide structures are shown to be formed by interactions
with water molecules during the thermal annealing of the GO. These studies are
providing important clues on the nature of GO.
Bio
KJ Cho is an associate professor of materials science and engineering and of physics.
Before joining UT Dallas in 2006, he was an assistant professor of mechanical
engineering and of materials science and engineering at Stanford University. His
research interests concern computational modeling of nanomaterials with applications to
nanoelectronic devices and renewable energy technology. For materials modeling, his
research group has developed an atomistic modeling method to simulate atomic
structures of nanomaterials and a tight binding method to calculate electronic structures
and quantum transport properties of nanoelectronic devices. Advanced first principles
quantum simulations methods (density functional theory) are used to investigate the
nanomaterials with quantitative accuracy and achieve fundamental understanding of
structure-property relationships.
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