There’s been no greater act of magic in technology than the sleight of hand performed by Moore’s Law. Electronic components that once fit in your palm have long gone atomic, vanishing from our world to take up residence in the quantum realm.
But we’re now brushing the bitter limits of this trend. In a paper published in Nature this week, scientists at Tsinghua University in Shanghai wrote that they’ve built a graphene transistor gate with a length of 0.34 nanometers (nm)—or roughly the size of a single carbon atom.
The gate, a chip component that switches transistors on and off, is a critical measure of transistor size. Previous research had already pushed gate lengths to one nanometer and below. By scaling gate lengths down to the size of single atoms, the latest work sets a new mark that’ll be hard to beat. “In the future, it will be almost impossible for people to make a gate length smaller than 0.34 nm,” the paper’s senior author Tian-Ling Ren told IEEE Spectrum. “This could be the last node for Moore’s Law.”
Etching a 2D Sandwich
Transistors have a few core components: the source, the drain, the channel, and the gate. Electrical current flows from the source, through the channel, past the gate, and into the drain. The gate switches this current on or off depending on the voltage applied to it.
Recent advances in extreme transistor gate miniaturization rely on some fascinating materials. In 2016, for example, researchers used carbon nanotubes—which are single-atom-thick sheets of carbon rolled into cylinders—and a 2D material called molybdenum disulfide to achieve a gate length of one nanometer. Silicon is a better semiconductor, as electrical currents encounter more resistance in molybdenum disulfide, but when gate lengths dip below five nanometers, electrons leak across the gates in silicon transistors. Molybdenum disulfide’s natural resistance prevents this leakage at the tiniest scales.
Building on this prior work, the researchers in the most recent study also chose molybdenum disulfide for their channel material and a carbon-based gate. But instead of carbon nanotubes, which are a nanometer across, they looked to go smaller. Unroll a nanotube and you get a sheet made of carbon atoms called graphene. Graphene has all kinds of interesting properties, one of which is excellent conductivity. The width and length of a graphene sheet are, of course, bigger than a nanotube—but the edge is a single carbon atom thick. The team cleverly exploited this property. READ MORE...
Transistors have a few core components: the source, the drain, the channel, and the gate. Electrical current flows from the source, through the channel, past the gate, and into the drain. The gate switches this current on or off depending on the voltage applied to it.
Recent advances in extreme transistor gate miniaturization rely on some fascinating materials. In 2016, for example, researchers used carbon nanotubes—which are single-atom-thick sheets of carbon rolled into cylinders—and a 2D material called molybdenum disulfide to achieve a gate length of one nanometer. Silicon is a better semiconductor, as electrical currents encounter more resistance in molybdenum disulfide, but when gate lengths dip below five nanometers, electrons leak across the gates in silicon transistors. Molybdenum disulfide’s natural resistance prevents this leakage at the tiniest scales.
Building on this prior work, the researchers in the most recent study also chose molybdenum disulfide for their channel material and a carbon-based gate. But instead of carbon nanotubes, which are a nanometer across, they looked to go smaller. Unroll a nanotube and you get a sheet made of carbon atoms called graphene. Graphene has all kinds of interesting properties, one of which is excellent conductivity. The width and length of a graphene sheet are, of course, bigger than a nanotube—but the edge is a single carbon atom thick. The team cleverly exploited this property. READ MORE...
