![]() ![]() They then etched into the sandwiched materials to create a step-the same shape as the stairs in your home-and in the process, exposed the edge of the graphene sheet in the vertical wall of the step, thus making an atomically thin gate. The aluminum oxide and silicon dioxide sandwiching the graphene act as insulators, effectively cutting off its electrical properties from the rest of the transistor. Then, using a graphene production method called chemical vapor deposition, they laid a sheet of graphene on top of the silicon dioxide and a layer of aluminum oxide on top of the graphene. The team cleverly exploited this property.įirst they laid down a layer of silicon dioxide for the base structure. The width and length of a graphene sheet are, of course, bigger than a nanotube-but the edge is a single carbon atom thick. ![]() Graphene has all kinds of interesting properties, one of which is excellent conductivity. Unroll a nanotube and you get a sheet made of carbon atoms called graphene. But instead of carbon nanotubes, which are a nanometer across, they looked to go smaller. Molybdenum disulfide’s natural resistance prevents this leakage at the tiniest scales.īuilding on this prior work, the researchers in the most recent study also chose molybdenum disulfide for their channel material and a carbon-based gate. 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. 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. Recent advances in extreme transistor gate miniaturization rely on some fascinating materials. The gate switches this current on or off depending on the voltage applied to it. Electrical current flows from the source, through the channel, past the gate, and into the drain. Transistors have a few core components: the source, the drain, the channel, and the gate. “This could be the last node for Moore’s Law.” Etching a 2D Sandwich “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. By scaling gate lengths down to the size of single atoms, the latest work sets a new mark that’ll be hard to beat. Previous research had already pushed gate lengths to one nanometer and below. The gate, a chip component that switches transistors on and off, is a critical measure of transistor size. 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. Electronic components that once fit in your palm have long gone atomic, vanishing from our world to take up residence in the quantum realm.īut we’re now brushing the bitter limits of this trend. I'm asking about general purpose CPU, so please do not suggest solutions like "single transistor is an cpu" or "single nand gate will do" etc.There’s been no greater act of magic in technology than the sleight of hand performed by Moore’s Law. Is 250-300 transistors an realistic number then?įell free to link any CPU's with documented low transistor count (even if its based on RTL logic and not transistors per so). I researched the topic for while and I was unable to find transistor level schematics for any other CPU, but I concluded that for example mc14500 (1bit CPU) is build from around 100 NAND gates, which would translate into around 200 transistors. What's the minimum number of transistors (more or less) needed to build simple general purpose CPU? Let's say 4 bit CPU with ~10 instructions (ADD, subtraction, MULTIPLY, move data to register, get data from register, xor, jump etc.).įor example 4004 used around 1200 transistors ( full transistor level schematics are avalible) but it supported around 46 instructions, so simpler CPU could have much less transistors. ![]()
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