Biomedical Engineering Reference
In-Depth Information
ballistic conduction on the scale of several hundred nanometers.
In fact, Li
. [87] have verified ballistic conductivity for several
nanotubes measuring 0.4 cm in length, showing that the excellent
low resistances of CNTs extend over large lengths. These different
types of CNTs can be contemplated for use as active channels of
transistors devices due to their high mobilities up to 10000 cm
et al
2
−1
,
at room temperature [88], or as very good conductors for advanced
electrical interconnections, due to their low resistivities [89-90];
Thess
Vs
. [91] calculated the resistivity of the ropes of metallic
SWCNTs to be in the order of 10
et al
−4
cm at 300 K. Moreover, CNTs
exhibit very high current-carrying capacities up to
Ω
~
9
−2
10
A cm
[92]. An overview of the physical properties of the CNTs is shown in
Table 9.1, as partially reported in ref. [93].
Table 9.1
Principal physical properties of the carbon nanotubes
Property
SWCNTs
By comparison
Size
0.6-1.8 nm in diameter
EBL creates lines 50 nm
wide, few nm thick
Density
1.33-1.40 g/cm
3
Aluminum 2.7 g/cm
3
Interlayer spacing (n, n) Armchair: 3.38 Å
(n, 0) Zigzag: 3.41 Å
(2n, n) Chiral: 3.39 Å
-
Tensile strength
45 billion Pa
Steel alloys break at
about 2 billion Pa
Resilience
Can be bent at large angle
without damage
Metal C-fibers fracture at
grain boundaries
Current carrying
capacity
Estimated at 1
×
10
9
A/cm
2
Cu wires burn out at
about 1
×
10
6
A/cm
2
Electrical resistivity
10
−4
Ω
cm at 300 K
1-50
cm at 300 K
(graphite)
µΩ
Electrical mobility
up to 10,000 cm
2
Vs
−1
, at
-
300 K
Field Emission
activate phosphors at 1 to 3 V
if electrodes spaced 1
Mo tips require fields
of 50 to 100 V/
µ
m
µ
m
Bandgap
~0.8 eV for diameter of 1 nm
~3.2 eV (ZnO bandgap)
Raman spectra
RBM at 150-200 cm
;
D-band at 1300-1400 cm
−1
-
−1
;
−1
G-band at 1500-1600 cm
;
Heat transmission
Predicted to be as high as
6000 Wm
Nearly pure diamond
transmits 3320 Wm
−1
−1
−1
−1
K
at RT
K
Temperature stability
Stable up to 2800°C in
vacuum, 750°C in air
Metal wires in microchips
melt at 600-1000°C
Cost
1500 $/g (2000)
500€/g (2010)
Gold was selling for about
10 $/g in October 2000
