Nanowires Candidate For Future After CMOS


From 2007, the semiconductor industry will continue to see performance improvements after CMOS gate scaling runs up against physical limits, said Hiroshi Iwai, a professor at the Tokyo Institute of Technology. Researchers can achieve higher transistor densities by pursuing reduced operating voltages, and nanowire or nanotube-based field-effect transistors (FETs) will eventually play key roles as well, he said. (H/T Sander Olson)

[University of Copenhagen] In 2009, Nanochemists from the Chinese Academy of Sciences and Nano-Science Center, Department of Chemistry at University of Copenhagen have developed nanoscale electric contacts out of organic and inorganic nanowires. In the contact they have crossed the wires like Mikado sticks and coupled several contacts together in an electric circuit. In this way they have produced prototype computer electronics on the nanoscale.

Nanowires 2007

FETs based on germanium, III-V materials or carbon nanotubes “would still be a little early for 2020, though they are good candidates afterwards,” said Iwai, a former Toshiba R&D manager.

Instead, devices could achieve high conduction at low voltages by using 1-D ballistic conduction, increasing the number of quantum channels and the number of nanowires or nanotubes in the channel.

FinFET-type structures with four conduction channels made of 1-D nanowires could achieve very high drive currents, he said, estimating that each wire could drive 77.5 mA at a 1 V power supply.

“This is an extremely high value,” he said, noting that already 21.6 mA/wire at 1.2 V was achieved experimentally by the Institute of Microelectronics (IME, Singapore), where the wire diameter equaled 3 nm. “By adjusting the wire width, the energy band mimimums become closer and we can increase the number of the conduction channels,” he said, with four bands likely for silicon-based nanowires.

By taking a vertical device in which the gate wraps around the channel and forming multiple nanowires to form discrete, complementary channels, charge-based devices could be extended much further than some are predicting, Iwai said.

Nanowires 2009

We already use various organic materials in, for example, flat screens, such as OLED (Organic Light Emitting Diode). The new results show how small and advanced devices made of organic materials can become. Thomas Bjørnholm, Director of the Nano-Science Center, Department of Chemistry at University of Copenhagen explains:

– “We have succeeded in placing several transistors consisting of nanowires together on a nano device. It is a first step towards realisation of future electronic circuitry based on organic materials – a possible substitute for today’s silicon-based technologies. This offers the possibility of making computers in different ways in the future.”

The researchers have used organic nanowires combined with the tin oxide nanowires in a so-called hybrid circuit. As in a Mikado game, the nanowires cross in a device consisting of 4-6 active transistor moieties. The devices have a low operational current, high mobility and good stability and that is essential in order for the material to be able to compete with silicon.

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