Scientists Create Transistors Without Semiconductors: Quantum Tunneling

First Posted: Jun 22, 2013 06:33 AM EDT

Electronic devices continue to get smaller. In fact, it's now possible to place millions of transistors on a single silicon chip. But these transistors can only become so small, halting progress when it comes to using them in tiny devices. Now, researchers have created transistors without semiconductors, solving the problem.

At the rate that current technology is advancing, it's likely that in 10 or 20 years, current transistors won't be able to get any smaller, according to the study's scientists. There's also an issue with semiconductors themselves; they waste a lot of energy in the form of heat. That's why the researchers decided to make a transistor with a nanoscale insulator with nanoscale metals on top.

In order to accomplish this, the researchers used laser and placed quantum dots (QDs) of gold as small as three nanometers across the top of a nanoscale insulator, boron nitride nanotubes (BNNTs). This substrate was perfect for the quantum dots due to its small size, controllable and uniform diameters and insulating nature. The researchers then fired up electrodes on both ends of the newly created QDs-BNNTs at room temperature. They found that, surprisingly, electrons jumped very precisely from gold dot to gold dot--a process known as quantum tunneling.

"Imagine that the nanotubes are a river, with an electrode on each bank. Now imagine some very tiny stepping stones across the river," said Yoke Khin Yap of Michigan Technological University, one of the researchers, in a news release. "The electrons hopped between the gold stepping stones. The stones are so small, you can only get one electron on the stone at a time. Every electron is passing the same way, so the device is always stable."

The team had actually made a transistor without a semiconductor. When sufficient voltage was applied, it switched to a conducting state. When the voltage was low or turned off, it reverted to its natural state as an insulator.

The findings could be huge for minimizing transistors in future electronic devices. In addition, the new transistors can actually work in conditions that aren't extreme; other quantum tunneling devices that have been developed have only operated at liquid-helium temperatures.

The findings are published in the journal Advanced Materials.

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