2009 Annual Report Vol.37 - 中研院物理研究所 - Academia Sinica

devices and to investigate possible applications of the fabricated nano-devices. In
the first category, we study superconductor-insulator phase-transition in arrays of
Josephson junction arrays, transport in superconducting single electron transistors and
in nanowires of various materials (such as silicon, carbon nanotube). In the second
category, attempts have been made on manipulation and detection of molecule
monolayer. In the following, we present high lights of our recent research works.
1. Electron hopping conduction in highly disordered carbon coils
The electric transport in a single carbon coil was measured from ambient
temperature to 64 mK. The temperature-dependent resistance was analyzed with the
Efros-Shklovskii variable range hopping model, indicating three-dimensional electron
hopping conduction in the disordered helical wires. The analysis also provides a basic
understanding of the electron transport with an electron hopping length of 5 nm inside
the disordered carbon coils. [Carbon 47, 1761-69 (2009).]
R o (kΩ)
625
80
70
60
50
40
R Rhop(nm) hop(nm)
15
10
5
123
T (K)
39
0
0 100 200
T(K)
300
16
7.7
30
0.2 0.3 0.4 0.5 0.6
T-¼ (K-¼ T ) -¼ (K-¼ )
2μm
4.2
0.7
Electric transport measurement of
carbon coils. (main panel) The
R0(T) dependence with a fitting to
ES-VRHC behavior at temperatures
below 94 K. Dashed curve shows
an extension to 300 K. The
exponent s and ES-temperature TES
are 0.1136 and 0.1744 K,
respectively. The corresponding
actual temperatures are labeled at
the top for reference. (upper inset)
The mean hopping distance as a
function of temperature, in which
the dotted curve shows an
extrapolation using the theory of
VRHC. (lower inset) An SEM
image of the measured carbon coil
of 150 nm wire diameter. The scale
bar is 2 μm.
2. Coulomb blockade behavior in an indium nitride nanowire with disordered
surface states
Meticulous Coulomb oscillations are observed in a single electron transistor based on
an individual indium nitride nanowire at low temperatures. While the device shows
single period Coulomb oscillation at high temperatures or at high bias voltages,
additional satellite peaks along with the main Coulomb peak appear at low
temperatures and low bias voltages. The quasiperiodic structure is attributed to the
mixing of dissimilar Coulomb oscillations arising from two serially coupled islands
26