Law-Defying Transistor Smashes Industry 'Limit', Measures Just 1nm (thestack.com)

An anonymous reader quotes a report from The Stack: U.S. researchers have unveiled the world's smallest transistor reported to date, combining a new mix of materials, which makes even the tiniest silicon-based transistor appear big in comparison. The team, led by the U.S. Department of Energy's Lawrence Berkeley National Laboratory, designed the minuscule transistor with a working one-nanometer gate -- far surpassing any industry expectation for reducing transistor sizes. In the scientific study, MoS2 transistors with 1-nanometer gate lengths, published today in the journal Science, the researchers describe a prototype device which uses a novel semiconductor material known as transition metal dichalcogenides (TMDs). The transistor structure uses a single-walled carbon nanotube as the gate electrode and molybdenum disulfide (MoS2) for the channel material, rather than silicon. "The semiconductor industry has long assumed that any gate below 5 nanometers wouldn't work, so anything below that was not even considered. This research shows that sub-5-nanometer gates should not be discounted. Industry has been squeezing every last bit of capability out of silicon. By changing the material from silicon to MoS2, we can make a transistor with a gate that is just 1 nanometer in length, and operate it like a switch," explained study lead Sujay Desai.

Comments

Re:what's this about effective channel length

[Plus1Entropy]

from the paper's abstract: "Simulations show an effective channel length of ~3.9 nm in the Off state". what does this mean? that the gate, in it's off state, needs 4nm or it will start interfering with nearby gates?

The word Gate is not referring to a logic gate (which is what it sounds like you're inferring), but to the Gate terminal of the transistor. When the correct polarity of voltage is applied to the Gate, the field effect causes a channel of charge carriers to form between 2 other terminals, the Source and Drain, allowing current to flow between them. The channel length refers to the distance between the Source and Drain terminals.

The channel length (as well as other parameters like the width, charge carrier mobility, etc.) determines how much current can flow between the Drain and Source when a given voltage is applied (i.e. resistance). By applying higher voltage to the Gate, you are narrowing the "effective" channel length (lowering the resistance).

When you switch transistors on and off, you are basically charging and discharging capacitors, which takes time. How much time is determined by the time constant, RC (resistance x capacitance). So, shorter channel length = lower resistance = smaller time constant = faster charge/discharge = higher speeds. That's why we make transistors smaller to make computers faster.