According to MIT, cubic boron arsenide (c-BA) is the best semiconductor ever identified—and perhaps even the best at all.
The shortage of semiconductors has once again reminded us how important these materials are to our species. that siliconespecially is absolutely ubiquitous; we find in all computer chipsfrom your connected watch to the biggest supercomputers in the world.
However, this almost ubiquitous material is far from ideal on every level. First, its thermal conductivity is anything but exceptional; it is for this reason that your computer must be constantly cooled.
In any case, it conducts electrons extremely well. However, contrary to what intuition suggests, this does not mean that its electrical conductivity is more ideal. In fact, silicon is much less welcoming to so-called electron “holes”.
It is a physical concept where the absence of an electron is treated as a particle, and the latter must be absolutely free of their movements so that a semiconductor can play its role. ” This is important because when you build a device you want a material where the electrons but also these holes move without resistance “, explains Gang Chen, co-author of a new study on the subject.
A semi to run them all
He and his team at the prestigious MIT recently conducted a series of experiments on a material with simply exceptional semiconductor properties: boron arsenide crystallized in cubic form (c-BA). To begin with, it presents a phenomenal thermal conductivityalmost 9 times greater than silicon (1300 W/mK against 149 W/mK at 28°C).
But this very interesting property had already been documented by materials science researchers. On the other hand, what these previous works did not show is that c-BA also offers one exceptional mobility for electrons and these famous “holes”.
For these reasons, the researchers argue that it is simply ” best semiconductor ever found, and possibly the best possible ! ” This is impressive, because I know of no other material, apart from graphene, that brings together all these properties. Chen says.
” Temperature is a major bottleneck for many electronic devicess,” says Jungwoo Shin, lead author of the study. “ Silicon carbide is replacing plain silicon in many major industries such as electric vehicles with Tesla thanks to its 3x higher thermal conductivity, despite electronic mobility being less important there “, he elaborates.
“ Imagine what we could achieve with cubic boron arsenide, with ten times greater thermal conductivity, but also much greater electronic mobility! It could change everything “, he breathes.
A potential as enormous as its industrial limits
Note that it is no accident that the researcher uses the conditional. Certainly, c-BA is a marvel of materials science. But it is also immeasurably harder to tame than our good old silicon.
First limit, and not least: boron arsenide is far from as abundant as silicon. Moreover, its synthesis is in crystalline form extremely complicated. Even for manipulators of great talent who have access to advanced equipment. Most of the time, these crystals have major structural defects that would prevent them from utilizing their full conductive potential.
The other concern is purity of the material. Today, silicon is very well known; over several decades of uninterrupted research, the industry has learned to produce it with a purity of approx. 99.99999999% (we’re talking about ” ten nines “). And at the moment, the researchers do not yet have the shadow of an idea that would allow them to achieve a score that is even comparable to cubic boron arsenide.
And even if they manage to circumvent these problems, they will not be out of the inn. They still need to answer a lot of basic questions before considering industrial use. The most important of these concerns stability and sustainability of this material.
Despite all the flaws of silicon, the industry knows that it remains stable; she can count on it for years. And it is a decisive factor at absolutely every level (supply, storage, lifetime, price, etc.).
The future prospects are still unclear
Even ignoring its other limitations, cubic boron arsenide could not be used on a large scale until manufacturers knew Exactly how it behaves over time – and by extension, how bad it can be profitable.
Suffice it to say that it is not the day after tomorrow that a new semiconductor is going to replace silicon; it will take more than an enormously promising piece of material to convince an entire industry to replace the bedrock it has stood on for decades.
” Silicon is the workhorse of the industry sums up Chen. ” Ok, we have a material that is simply better. But will it change the industry? We do not know. “Although it looks like the ideal semiconductor on paper,” if it can actually end up in a device and replace some of the current market… i think that still needs to be proven “, he concludes.
The text of the survey is available here.