Page 67 - Principles and Applications of NanoMEMS Physics

54 Chapter 2

typical for nanoparticles, then the charging energy would be close to the
thermal energy at 300K. The implication of this is that it may be impossible
to continuously inject charges into the capacitor when the charging energy
exceeds the ambient temperature. Rather, for an increasing applied voltage, a
charging event only occurs every time its magnitude exceeds the charging
energy of an electron; one enters the Coulomb blockade regime and the
current into the capacitor becomes pulse-like. The situation is illustrated in
Figure 2-4 with respect to the so-called single-electron box [69].

Tunnel
Tunnel
Barrier
Barrier
Gate
Gate
Q=-nq
Q=-nq
Electrode
Source Electrode
Source
Electrode
Electrode
V V
G G
Small C C 0 0
Small
Island
Island
(a)
Tunnel
Tunnel
Barrier
Barrier
Gate
Gate
q -nq
q -nq
e e
Electrode
Source
Source - - + + - - + + Electrode
Electrode + + - - + +
Electrode - -
- - + + - - + + V V G G
Small -q -q
Small
e e
Island
Island
(b)
C C C
0 0 0
Q=n q q
Q=n
V V V
G G G
C C C J J J
(c)
Figure 2-5. Voltage-controlled electron injection into metallic island. (a) V G =0. (b) V G >V C .
(c) Circuit model (After [68], [ 69].)