NyTeknik.se: The super circuits for the green transition – why Sweden is at the forefront

Link to NyTekni Article (in Swedish): The super circles for the green transition – why Sweden is at the forefront (nyteknik.se)

REPORTER: Charlotta von Schultz – 9 FEB 2023 AT 07.53

Jr-Tai Chen is the co-founder and CEO of Swegan, the Linköping company that is now building a factory to manufacture gallium nitride semiconductor materials.

Electric car manufacturers, the photovoltaic industry, telecom companies. Everyone is crying out for energy-efficient components that can withstand high voltages, frequencies, and temperatures. This gives silicon carbide and gallium nitride circuits a boost – and hopes are raised for a new era for semiconductor Sweden. Ny Teknik answers ten questions.

  1. Why is interest in silicon carbide and gallium nitride increasing?

Circuits made of silicon carbide and gallium nitride hit the usual silicon circuits on the fingers in a range of areas. They can handle higher voltages, are extremely energy efficient, stand up to higher temperatures while being lighter and smaller than the silicon circuits.

These characteristics make them highly interesting for manufacturers of electric cars, inverters for solar cells, power supplies for computers and mobiles and a number of other applications.

“The market is growing extremely strongly for both silicon carbide and gallium nitride. These components are needed for electrification and the green transition,” says Mikael Östling, professor of solid state electronics at KTH.

The materials can also handle high frequencies and are therefore used in applications such as radar, satellite communications and radio base stations in 5g networks.


Silicon carbide

Silicon carbide has the chemical designation SiC is a compound of the elements silicon, Si, and carbon, C.

The Swedish chemist Jacob Berzelius was the first to manufacture the material. The year was 1824.

The explanation behind all the advantages of the materials?

The wide band gap, which makes silicon carbide and gallium nitride usually called wide bandgap material, or WBG material for short.

After all, they are the most important components of the green transition.

  1. What is a bandgap – and why is it good if it’s big?

Okay, now we’re diving down to the atomic level. A material’s band gap controls how easily electrons can jump between the atom’s conduction band and valence bands. The narrower the band gap, the easier the electrons can jump and give rise to a current.

In a conductor, you absolutely do not want a large band gap, because then it will be sluggish to conduct the current. In an insulator, on the other hand, the electrons should stay in their place, and then the band gap needs to be very large.

The semiconductors are, as the name suggests, in between, and silicon carbide and gallium nitride have much wider band gaps than silicon, which is the material most semiconductors are made in. This means that the materials are able to maintain a much higher electric field strength, i.e. a higher voltage over a certain distance. In this way, they are perfect for different types of power electronics where high voltages are handled.

If you do not need such a high voltage, the voltage resistance can be useful in other ways. For example, you can shrink the size of transistors and diodes, which thus become both faster and more energy-efficient.

To top it off, the materials are very good at dissipating heat. It also contributes to the fact that the components can be made significantly smaller.

  1. Why aren’t all electronics made of silicon carbide and gallium nitride if the materials are so good?

Because silicon semiconductors can be manufactured significantly cheaper in enormously larger volumes. Silicon is therefore the obvious choice for, for example, microprocessors.

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The production of silicon wafers is facilitated by the fact that the crystals consist solely of silicon. Making crystals of even and high quality is much more difficult when it comes to composite materials such as silicon carbide and gallium nitride. Defects are formed, production volumes become smaller, discs become more expensive.

Therefore, silicon carbide and gallium nitride are used where the benefits are most advantaged. That is, in demanding applications with high voltages, frequencies or temperatures. And such applications are plentiful.


Gallium nitride

Gallium nitride has the designation GaN and consists of gallium, G, and nitrogen, N.

The Nobel Prize in 2014 went to three Japanese scientists who managed to manufacture efficient blue light-emitting diodes in gallium nitride.

4. Varför är elbilstillverkarna så heta på kiselkarbid?

One important reason is that silicon carbide gives electric cars a longer range, and interest in the material got a real boost in the automotive industry when Tesla introduced silicon carbide inverters in the Model 3 a few years ago. Since then, more and more vehicle manufacturers have embarked on the same path.

The silicon carbide circuits are used, among other things, in the inverters that convert the battery’s direct current into alternating current for the electric motor. In all conversions, losses occur, but they will be significantly lower if the inverter is made of silicon carbide instead of silicon. And less losses mean the energy in the battery lasts longer.

In addition, one can increase the switching frequency in the inverter, which makes it possible to reduce its size and weight. That’s good news because lower weight gives vehicles better performance.

Another growing market for silicon carbide is inverters in photovoltaic systems. There, lower losses and higher efficiency attract when the direct current from the solar cells is converted into alternating current. The bottom line is that more solar power can be fed to the grid.

  1. What are gallium nitride’s biggest markets?

A large emerging market for gallium nitride is chargers for mobile phones, computers, and other electronics. The chargers can be made more compact with less losses.

Often, circuits are used in which thin gallium nitride layers are grown on silicon substrates, which is a way to cut the cost.

Many gallium nitride circuits also end up in amplifiers for 5g base stations. Gallium nitride is also used, among other things, to manufacture microleds, minimal LEDs, which can be used in high-resolution screens.

Jr-Tai Chen is the co-founder and CEO of Swegan, the Linköping company that is now building a factory to manufacture gallium nitride semiconductor materials.

  1. How are Swedish companies doing in silicon carbide and gallium nitride?

“We are definitely at the forefront. Many companies have been started, we have seen several sales in the multimillion-dollar class and have trained lots of doctors, says KTH professor Mikael Östling, who is himself the co-founder of Transic.

Many of the companies have been spun off from KTH in Kista and from Linköping and Lund Universities. The background is partly that financiers such as SSF, the Foundation for Strategic Research, contributed large sums to the technology area around the turn of the millennium.

At the same time, ABB made a major investment in a silicon carbide factory in Kista. The company collaborated with researchers at both KTH and the University of Linköping.

Saab was also among the pioneers and started using gallium nitride in commercial radar systems as early as 2005. This development took place in collaboration with Chalmers.

ABB’s project did run into trouble and was shut down. But the knowledge lived on.

Several of the companies that have been started have been acquired, but many businesses are continued in Sweden under a new flag.

  1. What kind of Swedish newcomers are there?

Co-founder Richard Spengler at Epiluvac’s epitaxy equipment. Epiluvac

The latest example of success is Lund-based Epiluvac, which in early February was bought by American Veeco. The purchase price is SEK 670 million if all conditions are met. Epiluvac, founded in 2013, develops so-called epitaxy equipment to manufacture the active semiconductor layers on wafers of silicon carbide, SiC, and gallium nitride, GaN.

The KTH spin-off Transic was founded in 2005 to develop power transistors in silicon carbide. The company was sold six years later to American Fairchild for just over SEK 100 million. Nowadays, the company is called Onsemi – and still has operations in the Electrum lab in Kista.

In 2011, Ascatron started to develop a new manufacturing technology for power semiconductors in silicon carbide. Two years later, the company entered Ny Teknik’s prestigious 33-list of the country’s most promising development companies.

The company was bought in 2020 by the American II-VI, which is pronounced two six. The slightly nerdy name, referring to columns two and six of the periodic table, was changed last fall to Coherent. The silicon carbide business remains in the Electrum lab and is expanding its production of high-quality epitaxy layers.

In 2017, Kisab, Kiselkarbidi i Stockholm AB, was founded, which with a new manufacturing process produces substrates with very few defects. The company raised around SEK 80 million in the autumn of 2022 from, among others, the state-owned Industry fund and the Ikea Group’s venture capital company Ingka Greentech. Despite the name, Kisab has its roots at Linköping University.

The linköping researchers’ work also forms the basis for the Norrköping company Norstel, which was founded in 2005 and began manufacturing silicon carbide wafers a few years later. The company has been owned since 2016 by French-Italian ST Microelectronics, which still has a factory in Norrköping.

Sensic was spun off from Linköping University in 2007 and brought a silicon carbide gas sensor to the market. In 2014, the company was included in Ny Teknik’s 33-list.

Newcomer Teksic, founded in 2021 in Linköping, is developing new manufacturing methods that provide more silicon carbide faster.

Linköping is also home to Swegan, which was founded in 2014 around a technology for growing a thin layer of gallium nitride on top of a silicon carbide wafer, GaN-on-SiC on semiconductor jargon. The company made it onto Ny Teknik’s 33-list in both 2019 and 2020. This technology also has its roots in research at Linköping University. Swegan raised SEK 125 million in the autumn of 2022 to expand and build a new production facility.

In addition to Epiluvav, Lund also houses Epinovatech, which was founded in 2019, and develops a high-quality gallium nitride material.

  1. What are the challenges for silicon carbide and gallium nitride start-ups?

Bo Hammarlund is something of a serial entrepreneur in the field and is the co-founder of Transic, Sensic, Ascatron and Epiluvac, among others. He gives some examples of difficulties for start-ups in silicon carbide and gallium nitride

“You can be a super talented innovator, but you need good management that understands semiconductor technology as well. Sure, you can bring in a good CEO who has joined Handels, but that person may not find it so easy to familiarize themselves with the semiconductor world. You also have to go directly to the international market to find customers and financing,” says Bo Hammarlund.

  1. Do Swedish companies get any benefit from the EU’s Chips Act?

The European Commission has proposed the major European Chips Act to strengthen Europe’s position in semiconductors. The idea is that EUR 43 billion will be invested, and one of the targets is for 20% of world semiconductor production to take place in Europe, a significantly higher proportion than at present.

“Hopefully, the EU will take the final decision during our Swedish Presidency. With such a decision in place, we will see a clear increase in industrial investment in Europe. And if we keep our tongues firmly in our mouths, we may be able to release some money to strengthen our research environments and companies in Sweden,” says Mikael Östling.

I hope for a whole new era for semiconductor Sweden.

  1. Will there be any factories for silicon carbide and gallium nitride in Sweden?

“I hope for a whole new era for semiconductor Sweden. Some silicon factories will not be built in Sweden, it is so enormously expensive. But building a factory for gallium nitride or silicon carbide is not unrealistic, we can. You will get quite far with SEK 10 billion, says Mikael Östling and continues:

“Sure, 10 billion is a lot of money, but we have shown that we can make major industrial investments in this country if you look at the battery investments in the north. Then we should be able to invest in these semiconductors as well, they are the most important components of the green transition.”