Silicon, you have served us well, but soon your time will end, as we push through barriers you simply cannot overcome. Exactly what will replace you is still being determined, but researchers at Purdue University have designed a new kind of transistor made from indium-gallium-arsenide that is at least intriguing, if not amazing.
To reach the impressively small transistors we have now at 22 nm, the designs have gone vertical and are no longer the traditional 2D planes. This new design is also vertical, with three tiny nanowires stacked on top of each other, but goes a step further. Dubbed "4D" transistors by one of the researchers, this design actually shows improved performance when the transistors are built directly on top of each other.
This ability to stack transistors will obviously lead to faster processors as more transistors will be able to fit in the same area, but that is not the only way to fit more of these a die. The gate size for this design is just 20 nm, which may not be much smaller than the 22 nm of modern processors, but still is smaller.