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In-Depth Information
a
electrode
+
s
s
s
s
s
n
n
s
s
s
n
s
n
s
electrode
b
c
B
B
A
2
A
2
A
1
A
1
A
2
A
2
A
1
A
1
B
B
+
+
+
+
+
+
+
+
+
+
-
0
0
0
-
-
+
+
-
-
0
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-
-
Fig. 3.10 Structure of the Aviram molecular switch (a) and logic elements built on the basis of
this device (b and c)
The efficiency of such an element is defined by three fundamental properties.
The fragments of this element must be long enough to ensure their electronic
band structure. In other words, they should be similar to conductive polymers.
The structure of the molecule as a whole and of the nonconducting bridge
between the two fragments (Figs.
3.9
and
3.10
) must ensure the possibility of
electron tunneling at a fairly low potential, which converts the conducting form
to the nonconducting one and vice versa.
The switching of the fragments from one state to another must occur under the
influence of the potential applied to the microelectrodes located on the central axis
of the molecular complex.
Thus, the molecular component proposed by Aviram is a switching device with
two stable states, controlled by electric field. Aviram considered a number of logic
circuits which can be constructed on the basis of the proposed molecular element.
Two of them are shown in Fig.
3.10
.
