Researchers at IBM have fabricated a carbon nanotube transistor that mimics the design of modern silicon transistors but performs much better.
Transistors are the 鈥渟witches鈥� in electronic circuits, controlling the current that represents digital information. Making transistors smaller means more can be packed into circuits, resulting in more powerful computer chips.
But silicon transistors are expected to reach their physical limit of miniaturisation in the next couple of decades. Researchers hope nanotube devices may help keep circuits shrinking towards the atomic scale.
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Engineers at IBM鈥檚 Watson Research Center in New York fabricated a single-walled carbon nanotube field-effect-transistor (CNFET) designed to mirror the architecture of a metal-oxide semiconductor field-effect-transistor (MOSFET). The later is very common in modern silicon circuits.
Shalom Wind, at IBM, says the new nanotube transistor differs from previous designs. He says its gate, which controls the current, is on top of a nanotube and separated from the channel by a layer of silicon dioxide, rather than being shared between a number of transistors. This makes it possible to control each transistor individually.
Current boost
The research team found that the nanotube transistor鈥檚 gate could control the current better, meaning larger currents could be used. 鈥淭he more current you can drive, the more flexibility you have in circuit design,鈥� Wind told 快猫短视频. 鈥淭he implication is that you could have faster transistors.鈥�
The transistor鈥檚 novel design also means the researchers were able to fabricate transistors with different polarity. This is a crucial property of complementary metal oxide-semiconductor (CMOS) circuits, which are also very common.
Cees Dekker, a carbon nanotube researcher at Delft University of Technology in the Netherlands, says this is an important step towards building practical nanotube circuits. 鈥淚t鈥檚 interesting to make the comparison with silicon,鈥� he says. But he warns that many parameters are important in determining the efficiency of a transistor.
At present, the nanotube transistors are not smaller than the silicon ones, but the IBM researchers claim their results are a proof of principle and that the nanotube transistors will outperform them even when shrunk.
Journal reference: Applied Physics Letters (vol 80, p 3817)