Post Syndicated from Prachi Patel original https://spectrum.ieee.org/tech-talk/semiconductors/materials/atomsthick-transistors-get-faster-using-less-power
The researchers made the device by stacking a single sheet of graphene on a single layer of MoS2. This stacked region serves as the transistor channel, and the researchers deposit the gate electrode on top. The graphene monolayer acts as the source, while the molybdenum disulfide layer is the drain.
Other cold source materials such as 2D metals and electron-rich, n-doped semiconductors could also be used to break the 60 mV/decade limit, according to researchers from Shandong University who also presented their work at IEDM. Using simulations and modeling, they showed that n-doped graphene could bring the voltage down to 24 mV; even simply using n-doped silicon could bring it down to 33 mV.
Li says he and his colleagues chose MoS2 for their proof-of-concept device because it’s a 2D semiconductor that researchers have known and studied for a long time. Researchers from Taiwan Semiconductor Manufacturing Company also presented their latest findings on MoS2 transistors at IEDM.
These and other groups have not limited themselves to this 2D material. They are also working with materials such as tungsten disulfide (WS2) and black phosphorus. “If other materials work even better with our device technology, we will explore that,” says Buffalo’s Li.
Imec, in Leuven, Belgium, is placing its bets on WS2, which the company’s researchers believe should yield devices with the highest-ever performance. Two years ago, imec program director Iuliana Radu and her team developed a technique for placing a high-quality single layer of WS2 on a 300-mm silicon wafer. They now report that they can make WS2 transistors at wafer-scale. “The work paves the way towards industrial adoption of 2D materials,” they say.