in the nanospace to form the nanoscale Cu filament. Gap-type atomic switches using
not only inorganic materials but also polymer materials have been developed.
Switching behavior of the atomic switch consisting of solid-polymer-electrolyte
film, such as polyethylene oxide and Ag perchlorate complexes, has been
demonstrated [15].
3.1 Switch Operation Principle
It is described in detail here that although both-type atomic switches operate utilizing
local ion migration and its electrochemical reaction, the gapless-type atomic switch
operates with a mechanism different from that of the gap-type atomic switch [16].
Current-voltage (I-V) characteristics of the gapless-type atomic switches made of
stacked structures of Cu/Ta 2 O 5 /Pt layers and Ag/Ta 2 O 5 /Pt layers are shown in
Fig. 12a, b, respectively. The switches are achieved by formation and shrinkage of
bridges, which are made of Cu and Ag filaments in Ta 2 O 5 , between electrodes,
respectively. Both as-fabricated atomic switches showed resistances of 10 GΩ or
more. When the applied bias voltages to the Cu and Ag electrodes were first swept to
the positive polarity, the elements indicate the switches from high resistances (OFF
states) to the low resistances (ON states) as indicated by the blue (I-V) curves, which
are called SET operation. In these initial SET operations, bridges of metal filaments
(Cu and Ag filaments) are formed between the Cu, Ag and Pt electrodes, which are
called the “forming process”. Since the energies required to form the Cu, Ag
filaments are different, the voltages at the SET operation are different in
Fig. 12a, b. However, the mechanisms of these switches caused by the formation
and shrinkage of Cu and Ag filaments are the same. For example, the formation
mechanism of the Cu filament in Ta 2 O 5 at this SET operation is shown in
Fig. 12c. When a positive bias is applied to the Cu electrode, an anodic oxidation
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
Ag
electrode
Ag 2 S crystal
+ -
Ag +
Ag (metal) → Ag +
(Ag2S) + e -
Ag (metal) ← Ag +
(Ag2S) + e -
Pt
electrode
S -
Ag
filament
e -
Fig. 11 Switching
mechanism of the gap-less
type atomic switch using a
silver atom filament grown
by solid electrochemical
reaction [11]
12
K. Terabe et al.
not only inorganic materials but also polymer materials have been developed.
Switching behavior of the atomic switch consisting of solid-polymer-electrolyte
film, such as polyethylene oxide and Ag perchlorate complexes, has been
demonstrated [15].
3.1 Switch Operation Principle
It is described in detail here that although both-type atomic switches operate utilizing
local ion migration and its electrochemical reaction, the gapless-type atomic switch
operates with a mechanism different from that of the gap-type atomic switch [16].
Current-voltage (I-V) characteristics of the gapless-type atomic switches made of
stacked structures of Cu/Ta 2 O 5 /Pt layers and Ag/Ta 2 O 5 /Pt layers are shown in
Fig. 12a, b, respectively. The switches are achieved by formation and shrinkage of
bridges, which are made of Cu and Ag filaments in Ta 2 O 5 , between electrodes,
respectively. Both as-fabricated atomic switches showed resistances of 10 GΩ or
more. When the applied bias voltages to the Cu and Ag electrodes were first swept to
the positive polarity, the elements indicate the switches from high resistances (OFF
states) to the low resistances (ON states) as indicated by the blue (I-V) curves, which
are called SET operation. In these initial SET operations, bridges of metal filaments
(Cu and Ag filaments) are formed between the Cu, Ag and Pt electrodes, which are
called the “forming process”. Since the energies required to form the Cu, Ag
filaments are different, the voltages at the SET operation are different in
Fig. 12a, b. However, the mechanisms of these switches caused by the formation
and shrinkage of Cu and Ag filaments are the same. For example, the formation
mechanism of the Cu filament in Ta 2 O 5 at this SET operation is shown in
Fig. 12c. When a positive bias is applied to the Cu electrode, an anodic oxidation
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
S -
Ag
electrode
Ag 2 S crystal
+ -
Ag +
Ag (metal) → Ag +
(Ag2S) + e -
Ag (metal) ← Ag +
(Ag2S) + e -
Pt
electrode
S -
Ag
filament
e -
Fig. 11 Switching
mechanism of the gap-less
type atomic switch using a
silver atom filament grown
by solid electrochemical
reaction [11]
12
K. Terabe et al.