"Our device can solve all problems that today's semiconductor devices have," Tsuyoshi Hasegawa of the National Institute for Materials Science told nanotechweb.org. "By reducing the size of the mechanical device to the atomic scale, it shows much better performance than that of the semiconductor devices."
Hasegawa and colleagues operated their quantized conductance atomic switches by controlling the formation of an atomic bridge between two wires spaced about 1 nm apart. One wire was platinum while the other was silver sulphide (Ag2S), which is a solid electrolyte. Applying a positive bias voltage to the silver sulphide caused a silver nano-protrusion to form, creating a bridge between the two wires.
The presence of this bridge boosted the conductance between the wires, putting the switch into its "on" state. Applying a negative voltage, on the other hand, caused the silver bump to shrink, breaking the atomic bridge and switching off the device.
The team found that the devices worked repeatedly - more than 105 times - and in both air and a vacuum. The switches worked at speeds of 1 MHz, similar to those of today's semiconductor devices. The team reckons its switches could function at 1 GHz, although the capacitance of the wires meant that it was not possible to measure speeds this fast.
"Since an atom is much heavier than an electron, people think that atomic switches should show less performance than electronic devices," said Hasegawa. "We had to break the common sense by showing the data."
The researchers also made AND, OR and NOT logic gates by combining the switches.
"Our device can be used in most electronic products, such as memories and logic circuits for computers," said Hasegawa. "It can be used as a component of current devices and also to make conceptually new computers."
By using pulsed bias voltages to tailor the length of the nano-protrusion, the team was able to switch between four of the quantized conductances of each device in a 1 x 2 array. The system worked as an adder circuit, and also as a multi-state memory - it memorized 16 states using just two switches.
Other solid electrolytes, such as copper sulphide, were also suitable for forming the switches.
According to Hasegawa, the researchers are now aiming to use their switches in commercial devices, in conjunction with an electronics company. In the longer term, they plan to work on conceptually new computers.
The researchers reported their work in Nature.