Following trigate, or 3D transistors, there could be 4D transistors. But don't get excited just yet.
Researchers at Purdue University said that they succeeded in replacing silicon in transistors and create a path to much smaller chip structures. Instead of silicon, the team at Purdue used indium-gallium-arsenide that could become a critical material for the production of semiconductors below 10 nm. A prototype built at Purdue has been made in a 20 nm process.
According to Peide Ye, a professor of electrical and computer engineering at Purdue, three indium-gallium-arsenide wires were stacked on top of each other, while being progressively shorter to the top. Including the tapered cross section, the structures resembles the shape of a Christmas tree. So, why would we call this a 4D transistor? Here is the explanation in Peide's words:
"A one-story house can hold so many people, but more floors, more people, and it's the same thing with transistors," Ye said. "Stacking them results in more current and much faster operation for high-speed computing. This adds a whole new dimension, so I call them 4D." Curb your enthusiasm. No time travel yet.
However, indium-gallium-arsenide is, in fact, an interesting material to scale chip structures and, as Peide points out, silicon may run into physical limits in the 10 nm neighborhood. Whether that will be the case or not, we know that there are solutions that will keep Moore's Law alive for some time.