5 Enabling Materials By Dimensionality: From 0D to 3D Carbon-Based. . .
175
5.6.1 Two Case Studies: Transport Properties of Diamond and
Graphite
First we consider the electron transport properties from reflection electron energyloss spectroscopy (REELS) measurements of diamond and graphite films. Indeed,
while graphene and other 2D materials are considered the most promising replacements of silicon in future electronics [99], difficulties in finding scalable, cheap
and safe techniques to grow high-quality graphene sheets currently hamper the
hypothetical potential of this 2D material. Furthermore, in order to use graphene
in microelectronic applications, a band gap must be opened [47, 48]. In this regard,
other naturally occurring allotropic forms of carbon, such as diamond and graphite,
could be used as viable candidates for an all-carbon electronics.
For example, diamond, owing to several ideal characteristics, such as large thermal conductivity, high charge mobility, wide band gap, optical isotropic structure
and robustness, can be considered also a competitor in the carbon-based revolution
for enhancing the performances of electronic devices. On the other side, graphite
is the most stable naturally occurring carbon allotrope, characterized by a layered
architecture with both strong in-plane sp 2 -bonds, comparable in cohesive energy
to those found in diamond, and weak interplanar bonds that make it soft and
malleable as well as anisotropic to external perturbations. Furthermore, graphite
shows optimal heat, large electrical conductivity and high strength and stiffness even
above 3000 ◦ C.
5.6.1.1 The Dielectric Response of Materials
The study of charge transport in solids is of paramount importance in several
applications, ranging from materials characterization via electron microscopy and
spectroscopy to the production of optimally designed electronic devices by controlling the energy transfer scattering processes that occur in different energy ranges
[100–102].
In this regard, we notice that the analysis of the collision events taking place
within a solid is based on the accurate assessment of the frequency-dependent
dielectric function, which links microscopic properties, such as the band structure of
solids, to macroscopic features that are the direct outcome of spectroscopic experiments, such as the absorption coefficient, the surface impedance or the electron
energy loss. Indeed, the dielectric function (W, q), where W is the energy loss
and q the transferred momentum, provides access to the full electronic excitation
spectrum of the material in both energy and momentum space. Furthermore, we
observe that the dielectric function is the only material property necessary to assess
the inelastic cross sections. In particular, the real part of the dielectric function []
describes the screening (i.e. the polarizability) of the medium, while the imaginary
part [] the absorption. In general, single-electron excitations, such as excitons,
interband excitations and core-hole ionizations, are connected to the maxima of
175
5.6.1 Two Case Studies: Transport Properties of Diamond and
Graphite
First we consider the electron transport properties from reflection electron energyloss spectroscopy (REELS) measurements of diamond and graphite films. Indeed,
while graphene and other 2D materials are considered the most promising replacements of silicon in future electronics [99], difficulties in finding scalable, cheap
and safe techniques to grow high-quality graphene sheets currently hamper the
hypothetical potential of this 2D material. Furthermore, in order to use graphene
in microelectronic applications, a band gap must be opened [47, 48]. In this regard,
other naturally occurring allotropic forms of carbon, such as diamond and graphite,
could be used as viable candidates for an all-carbon electronics.
For example, diamond, owing to several ideal characteristics, such as large thermal conductivity, high charge mobility, wide band gap, optical isotropic structure
and robustness, can be considered also a competitor in the carbon-based revolution
for enhancing the performances of electronic devices. On the other side, graphite
is the most stable naturally occurring carbon allotrope, characterized by a layered
architecture with both strong in-plane sp 2 -bonds, comparable in cohesive energy
to those found in diamond, and weak interplanar bonds that make it soft and
malleable as well as anisotropic to external perturbations. Furthermore, graphite
shows optimal heat, large electrical conductivity and high strength and stiffness even
above 3000 ◦ C.
5.6.1.1 The Dielectric Response of Materials
The study of charge transport in solids is of paramount importance in several
applications, ranging from materials characterization via electron microscopy and
spectroscopy to the production of optimally designed electronic devices by controlling the energy transfer scattering processes that occur in different energy ranges
[100–102].
In this regard, we notice that the analysis of the collision events taking place
within a solid is based on the accurate assessment of the frequency-dependent
dielectric function, which links microscopic properties, such as the band structure of
solids, to macroscopic features that are the direct outcome of spectroscopic experiments, such as the absorption coefficient, the surface impedance or the electron
energy loss. Indeed, the dielectric function (W, q), where W is the energy loss
and q the transferred momentum, provides access to the full electronic excitation
spectrum of the material in both energy and momentum space. Furthermore, we
observe that the dielectric function is the only material property necessary to assess
the inelastic cross sections. In particular, the real part of the dielectric function []
describes the screening (i.e. the polarizability) of the medium, while the imaginary
part [] the absorption. In general, single-electron excitations, such as excitons,
interband excitations and core-hole ionizations, are connected to the maxima of