Introduction to Nanotechnology

352 NANOMACHINES AND NANODEVICES
1
1'3 1.1
h
u)
E"
a
c m
1
c
i
w
a
0
-0.1 t-I " ' I ' ' ' ' I ' ' ' ' I ' ' I ' I ' ' ' ' I ' ' ' 1 1
-0.5 0 0.5 1 1.5 2 2.5
VOLTAGE (V)
Figure 13.19. Current-voltage characteristics of the electronic switch shown in Fig. 13.18.
[Adapted from J. Chen, Science 286, 1550 (1999).]
To fabricate this switch, an aluminum electrode was made by lithographically
patterning 0.6-pm-diameter aluminum wires on a silica substrate. This electrode was
then exposed to oxygen to allow a layer of A1203 to form on it. Next a single
monolayer of the roxatane molecule, such as the one shown in Fig. 13.20, was
deposited as a Langmuir-Blodgett film, which was discussed in Chapter 10. Then a
5-pm layer of titanium followed by a thicker layer of aluminum were evaporated
through a contact mask using electron beam deposition.
Figure 13.22 shows the current-voltage characteristics of this device. The applica-
tion of -2 the read mode, caused a sharp increase in current. The switch could be
- +ec---
-e-
4PFe
Ann
ooooT7b
I I
Figure 13.20. Roxatane molecule used in a switch illustrated in Fig. 13.21 to make molecule-
based logic gates. [Adapted from C. P. Collier et al., Science 285, 391 (1999).]