number can be alternately controlled between 1 and 2 by precisely controlling the
growth and shrinkage of the Ag cluster on the STM tip.
To apply the repeatable switching between these quantum number to interesting
device function, 1 Â 2 array atomic switches with the cross-bar structure consisting
Ag/Ag 2 S nanowire and two Pt nanowires were fabricated [1]. The structure is the
same as that in Fig. 6. Each atomic switch exhibits quantized conductance by
precisely controlling the applied positive and negative pulse voltages. Quantum
numbers can be arbitrarily switched accordingly by applying voltages of appropriate
polarity and magnitude in a pulsed manner. Figure 8 shows that 4 Â 4 ¼ 16 states
can be obtained by connecting two atomic switches capable of producing four kinds
of quantum number, from 0 to 3. This result shows that multi-valued memory and
adder circuit can be developed by using this function.
2.4 Logic–Gate Operation
By using one or two gap-type atomic switches, it is possible to make basic logic
gates for logic operation of the computer [1]. Figure 9a–c show the structures of the
logic gates AND, OR, NOT and their experimental operations, respectively. Here, a
value of 1 in these figures indicates a state where voltage is applied to the input
Fig. 8 1 Â 2 array of gap-type atomic switches formed at cross-points of Ag/Ag 2 S wire and Pt
wires. States of the quantized conductance of these atomic switches can be changed independently
from N ¼ 0 to N ¼ 3 [1]
Invention and Development of the Atomic Switch
9
growth and shrinkage of the Ag cluster on the STM tip.
To apply the repeatable switching between these quantum number to interesting
device function, 1 Â 2 array atomic switches with the cross-bar structure consisting
Ag/Ag 2 S nanowire and two Pt nanowires were fabricated [1]. The structure is the
same as that in Fig. 6. Each atomic switch exhibits quantized conductance by
precisely controlling the applied positive and negative pulse voltages. Quantum
numbers can be arbitrarily switched accordingly by applying voltages of appropriate
polarity and magnitude in a pulsed manner. Figure 8 shows that 4 Â 4 ¼ 16 states
can be obtained by connecting two atomic switches capable of producing four kinds
of quantum number, from 0 to 3. This result shows that multi-valued memory and
adder circuit can be developed by using this function.
2.4 Logic–Gate Operation
By using one or two gap-type atomic switches, it is possible to make basic logic
gates for logic operation of the computer [1]. Figure 9a–c show the structures of the
logic gates AND, OR, NOT and their experimental operations, respectively. Here, a
value of 1 in these figures indicates a state where voltage is applied to the input
Fig. 8 1 Â 2 array of gap-type atomic switches formed at cross-points of Ag/Ag 2 S wire and Pt
wires. States of the quantized conductance of these atomic switches can be changed independently
from N ¼ 0 to N ¼ 3 [1]
Invention and Development of the Atomic Switch
9