Has MIT found the ultimate semiconductor?

According to MIT, cubic boron arsenide (c-BA) is the best semiconductor known – and perhaps the best of all.

The shortage of semiconductors reminds us once again how important these materials are to our species. the silicon, in particular, is absolutely omnipresent; we see in all computer chipsfrom your connected watch to the world’s largest supercomputer.

However, this almost universal material is not very good on all levels. For starters, its thermal conductivity is exceptional; it is for this reason that your computer must always be cooled.

At least it conducts electrons very well. But contrary to what intuition suggests, this does not mean that its electrical conductivity is better. In fact, silicon is not very receptive to so-called electron “holes”.

This is a physical concept where the loss of an electron counts as a particle, and the latter must be free in their movements so that a semiconductor can play its role. ” This is important because when you build a device, you want to have a material through which the electrons, but also these holes travel without resistance “, explained Gang Chen, co-author of a new study on the subject.

A semi to drive them all

He and his team at the prestigious MIT recently conducted a series of experiments on a material with unique semiconductor properties: boron arsenide crystallized in cubic form (c-BA). To begin with, it presents a exceptional thermal conductivityalmost 9 times greater than silicon (1300 W/mK against 149 W/mK at 28°C).

But this very interesting property has already been documented by materials science researchers. On the other hand, what the previous works failed to show is that c-BA also offers a extraordinary movement of electrons and these famous “holes”.

For these reasons, researchers claim that it is only ” best semiconductor found, and possibly the best possible ! ” This is surprising, because I do not know of any other material, except graphene, that combines all these properties. Chen said.

Temperature is a major bottleneck for many electronic devicess,” said Jungwoo Shin, lead author of the study. “ Silicon carbide has replaced simple silicon in many major industries, such as electric vehicles with Tesla thanks to its 3x higher thermal conductivity, despite the fact that electronic performance is not very important there “, he detailed.

Imagine what we can achieve with cubic boron arsenide, which has ten times greater thermal conductivity, but also greater electronic mobility! It could change everything “, he breathed.

© Laura Ockel – Unsplash

A potential as great as its industry limitations

Note that it is no coincidence that the researcher used the condition. In fact, c-BA is a marvel of materials science. But it is much more difficult to domesticate than our good old silicon.

First limitation, and not the least: boron arsenide is far from as abundant as silicon. In addition, its synthesis in crystalline form very complicated. Even for highly talented manipulators with access to advanced equipment. Most of the time, these crystals have many structural defects that prevent them from exploiting their full conductive potential.

Another concern is purity of the material. Today, silicon is well known; over decades of relentless research, the industry has learned to produce it with a purity of approximately 99.99999999% (we’re talking about ” ten nine “). And at the moment, the researchers do not have a shadow of an idea that would allow them to achieve a score comparable to cubic boron arsenide.

And even if they can solve these problems, they can’t get out of the inn. They still need to answer several fundamental questions before considering industrial use. The most important of these concerns the strength and the endurance of this material.

Despite all of silicon’s flaws, the industry knows it remains strong; he could count on it for years. And this is a key factor at all levels (supply, storage, life span, price, etc.).

Silicon remains the star of semiconductors, and that won’t change. © Anton Maksimov 5642.su
– Unsplash

Future prospects are still unclear

Even ignoring its other limitations, cubic boron arsenide could not be used on a large scale until known to manufacturers. exact how it behaves over time – and by extension, how bad it is favorable.

Suffice it to say that it won’t be tomorrow before a new semiconductor comes along to replace silicon; it will take more than one big promising material to convince an entire industry to replace the bedrock it has stood on for decades.

Silicon is the workhorse of the industry Chen summarized. ” Ok, we have a better material. But will it move the industry? We don’t know. “Although it looks like the ideal semiconductor on paper,” if it can really end up being a device and replace some in the current market… I guess that remains to be proven “, he concluded.

The text of the study is available here.

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