It is no doubt that Moore's Law has been a driving force of technological and social change, productivity, and economic growth that are hallmarks of the late-twentieth and early twenty-first centuries.

However, with the continued advances of the semiconductor industry, Moore's Law has been questioned to varying degrees, and even some voices say that "Moore's law is over”. Is Moore's Law coming to an end? Let’s look at Professor Greer’s view on Moore's law.

On September 27,2019, Jim Greer, Li Dak Sum Chair Professor in Advanced Electronic Materials and Devices, was invited by Institute for Molecular Science and Engineering (IMSE) of Imperial College London to attend IMSE Highlight Seminar and share his opinion on Moore’s Law. In his IMSE Highlight Seminar, Professor Greer mentioned that, so far, solutions have involved designs requiring new types of materials. However, finding and implementing in manufacturing an appropriate material can take 10 years or more.

One solution outlined in Professor Greer's seminar was a new design of transistor: the so-called nano-wire transistor. One version is the "junctionless" nanowire transistor, developed at the Tyndall National Institute in Ireland, which is a nanowire-based transistor that has no junctions which are essential for conventional transistors. Junctions are difficult to fabricate at very short lengths, and, because they are a significant source of current leakage, they waste significant power and heat. Eliminating junction improves manufacturability and holds the promise of cheaper and smaller microchips.

The junctionless nanowire transistor uses a simple nanowire of silicon surrounded by an electrically isolated "wedding ring" gate that controls the flow of electrons through the wire, akin to squeezing a garden hose to stop the flow of water. The nanowire is heavily doped, making it an excellent conductor. Crucially the gate, depletes the underlying silicon nanowire thereby preventing carrier flow past the gate.

However, new manufacturing challenges still exist for these junctionless devices. Although in theory it physically works, per Professor Greer, it is very difficult to make at extremely long length scales since it requires doping – at small length scales, this means the introduction of just a few atoms per transistor. Looking to the future, Professor Greer predicted that to continue the insatiable need for more transistors, transistors would be stacked on top of each other.