Moore’s Law’s Saving Grace: The Metal-Air Transistor

An Interview with Dr. Shruti Nirantar PhD/Research Fellow RMIT

When one type of technology is about to plateau, another one usually steps in to take its place. This is what’s happening in the chip sector with semiconductor transistors right now. Modern day electronics have relied on semiconductor transistors, which work by forcing electrons to move through the use of a semiconducting material like silicon. For some time, this has worked well. Following Moore’s Law, the number of transistors on a microchip has roughly doubled every couple of years, while prices have decreased. However, as more transistors are being squeezed onto one chip, they are getting close to hitting a plateau in terms of performance capability and size. This is making room for a new type of transistor: the metal-air transistor. In an interview with Dr. Shruti Nirantar, one of the leading experts in the field, we discussed how these transistors work and how they can ease some of the problems in modern technology.  

Metal-air transistors are basically nanoscale vacuum tubes. The concept behind this is not entirely new. Vacuum tubes were the go-to transistors prior to the invention of the semiconductor transistor. A vacuum is faster than a physical medium at transporting electrons, but in the past, there was no technology to scale them down to a nano size. Metal-air transistors are changing that. They use the properties of a vacuum to force electrons to move on the desired path. They do this by using a nanoscale gap between metal electrodes that is smaller than the mean-free path of electrons. In this way, the electrons automatically move along the correct path without a need to be in a vacuum. Dr. Nirantar described it using this analogy: just as the tallest building in a city attracts lightning, the points in the transistor attract electrons. 

With no need for a physical medium, this clears up some major problems in the chip sector. Metal-air transistors eliminate the need for semiconductors and substrate materials, the main causes of the current chip shortage. Without the need to drag electrons through a physical medium, these chips use less power and are much faster. The technology also allows for many more transistors to be placed on a single chip, thus preserving Moore’s Law as current transistors have reached their size limits.

The good news is that manufacturing these transistors would not be that much different than manufacturing other transistors. The same equipment could be used with some modifications and changes to the assembly sequence. This would allow foundries like TSMC to manufacture metal-air transistors without many revisions to their current processes. 

These transistors seem to be the future of electronics. With some funding and key partnerships, they will probably take over the electronics market in the next decade.