But this work is important to show that we are no longer limited to a 5-nanometer gate for our transistors. We also have not developed self-aligned fabrication schemes for reducing parasitic resistances in the device. We have not yet packed these transistors onto a chip, and we haven’t done this billions of times over. “This work demonstrated the shortest transistor ever,” said Javey, who is also a UC Berkeley professor of electrical engineering and computer sciences. Transmission electron microscope image of a cross section of the transistor, showing the edge of a 1-nanometer carbon nanotube gate and the molybdenum disulfide semiconductor separated by zirconium dioxide, which is a dielectric insulator. 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.” Industry has been squeezing every last bit of capability out of silicon. “This research shows that sub-5-nanometer gates should not be discounted. “The semiconductor industry has long assumed that any gate below 5 nanometers wouldn’t work, so anything below that was not even considered,” said study lead author Sujay Desai, a graduate student in Javey’s lab. The development could be key to keeping alive Intel co-founder Gordon Moore’s prediction that the density of transistors on integrated circuits would double every two years, enabling the increased performance of our laptops, mobile phones, televisions, and other electronics. We demonstrated a 1-nanometer-gate transistor, showing that with the choice of proper materials, there is a lot more room to shrink our electronics.” “The gate length is considered a defining dimension of the transistor. “We made the smallest transistor reported to date,” said faculty scientist Ali Javey at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and lead principal investigator of the Electronic Materials program in Berkeley Lab’s Materials Science Division. Based on the voltage applied to the gate, it switches the channel (the portion of the MoS2 semiconductor just above the carbon nanotube) on and off, via a dielectric (zirconium oxide, green), operating in a manner similar to a capacitor. Current flows through the semiconductor (MoS2, represented by the yellow molecular model) from the source to the drain.

Transistors consist of three terminals: a source (left), a drain (right), and a gate (the carbon nanotube, black, below). These properties help improve the control of the flow of current inside the transistor when the gate length is reduced to 1 nanometer. MoS2 can also be scaled down to atomically thin sheets, about 0.65 nanometers thick, with a a larger band gap and lower dielectric constant, a measure reflecting the ability of a material to store energy in an electric field (similar to a capacitor). But with a gate length below 5 nanometers in length, a quantum mechanical phenomenon called tunneling kicks in, and the gate barrier is no longer able to keep the electrons from barging through from the source to the drain terminals, so the transistor cannot be turned off.Įlectrons flowing through MoS2 are heavier, so their flow can be controlled with smaller gate lengths. (SWCNTs are hollow cylindrical tubes with diameters as small as 1 nanometer.)Ĭompared with MoS2, electrons flowing through silicon are lighter and encounter less resistance. The breakthrough was achieved by creating a 2D (flat) semiconductor field-effect transistor using molybdenum disulfide (MoS2) instead of silicon and a 1D single-walled carbon nanotube (SWCNT) as a gate electrode, instead of various metals. (One nanometer is the diameter of a glucose molecule.) Until now, a transistor gate size less than 5 nanometers has been considered impossible because of quantum tunneling effects. The first transistor with a working 1-nanometer (nm) gate* has been created by a team led by Lawrence Berkeley National Laboratory (Berkeley Lab) scientists. Schematic of a transistor with molybdenum disulfide semiconductor and 1-nanometer carbon nanotube gate.

Smallest transistor gate