Thursday, January 27

Silicon carbide semiconductors: what are their properties and why are they a valuable ally for the electric car


The development that the technology involved in the production of semiconductors has undergone during the last two decades is astonishing. And, far from slowing down, is accelerating as a consequence of the growing demand for integrated circuits that are being promoted by the information technology or automobile industries, among others.

Silicon is king in the semiconductor kingdom since it dethroned germanium in the 1960s and established itself as the semiconductor with the most potential and the one most used by the electronics industry. Nevertheless, we already have very interesting alternatives to conventional silicon semiconductors with which we are all somewhat familiar.

The development that semiconductor technology is experiencing is accelerating as a result of the growing demand for integrated circuits

One of them is gallium arsenide. Unlike silicon, it is not an elemental semiconductor because it is not made up of a single chemical element: it is composed of gallium (Ga) and arsenic (As). In any case, the properties that make it attractive are the high mobility of its electrons when the appropriate conditions are given, its high saturation speed, and, in addition, gallium arsenide transistors can work at frequencies above 250 GHz, which is quite an impressive figure.

However, these are by no means the only promising semiconductors beyond the high-purity silicon used by most IC manufacturers. Precisely, and although a priori it sounds a bit strange, one of the semiconductors that is getting the attention of the chip industry is the product of introduce carbon atoms in the crystalline structure of silicon, making it less pure, but, in certain usage scenarios, more attractive.

Silicon carbide: these are the properties that have put it in the spotlight

Actually, this compound is not new. It was discovered by the Swedish chemist Jöns Jacob Berzelius in 1824 while working on a new procedure that sought to synthesize diamonds, and its large-scale production began in 1890 at the hands of the American chemist Edward Goodrich Acheson. Its physicochemical properties have been well known for over a century, but it has been current demand for semiconductors the one that has put him back in the spotlight.

Like gallium arsenide, silicon carbide is not an elemental semiconductor because it is not made up of a single chemical element. As I mentioned a bit above, contains silicon and carbon, and in nature we can find it in a very rare mineral known as moissanite in homage to Henri Moissan, the French chemist who accidentally found it in 1893.

By introducing carbon atoms into the crystalline structure of ultrapure silicon, its physicochemical properties are altered.

In practice, by introducing carbon atoms into the crystalline structure of ultrapure silicon, its physicochemical properties are altered, allowing free electrons to move further and at a higher speed. This property makes silicon carbide semiconductors capable of working with higher switching frequency than pure silicon chips. However, this is not all.

Another essential characteristic of these semiconductors is that they dissipate significantly less energy in the form of heat than the latter. This property allows us to intuit how attractive they are in the field of the production of power semiconductors, in which it is essential to manage energy in the most efficient way possible. A final property of silicon carbide semiconductors that is worth not overlooking is their high structural stability to thermal stress.

Carbidesilicon wafer

A valuable ally ready to disembark in the electric car

The physicochemical properties of silicon carbide that we have just investigated make it very attractive for a very wide range of applications, but there is one in particular that can benefit from this compound in a profound way: the electric car. And it is that the integration of power semiconductors that are capable of managing energy in a more efficient way is crucial in any device in which it is necessary to reduce energy consumption in order to extend its autonomy as much as possible.

Bosch will begin large-scale production of silicon carbide semiconductors at its plant in Reutlingen (Germany) this December.

In addition, due to the fact that during their operation they dissipate less energy in the form of heat than high purity silicon semiconductors, silicon carbide chips can work hand in hand with more modest and less bulky cooling systems, which, on paper , it should have a beneficial impact both in cost and weight of the vehicles that will bet on them.

As we have just seen, the theory sounds good, but the most interesting thing is that the German company Bosch just announced that during this month of December will start large-scale production of silicon carbide semiconductors at its plant in Reutlingen (Germany). According to this company, a good part of its production will go to electric car manufacturers, who will be able to increase, according to Bosch, the autonomy of their vehicles by an average of 6% by replacing pure silicon semiconductors with silicon carbide ones.

Images | Bosch

More information | Bosch



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