More juice, fewer emissions: towards greener power devices
Power electronics are behind many of the key innovations which will be crucial for Europe’s green transition. Used to convert electricity, ‘green’ applications of power electronic devices range from electric cars to solar power systems. The design of new materials plays an important role in making these devices more efficient and sustainable. The semiconductor cubic silicon carbide (3C-SiC) has emerged as a candidate with high potential for improving power efficiency for devices operating at voltages between 100 and 1 200 V. The EU-funded CHALLENGE project (3C-SiC Hetero-epitaxiALLy grown on silicon compliancE substrates and 3C-SiC substrates for sustaiNable wide-band-Gap powEr devices) has now taken decisive steps towards turning it into a marketable technology. “We have developed a new technology for the creation of large 3C-SiC wafers which can be further developed in the future to realise a commercial material for power devices,” explains Francesco La Via, research director at the Institute for Microelectronics and Microsystems at the Italian National Research Council, which hosted the project.
The wafers are grown using heteroepitaxy, a process by which one kind of crystal is grown on the surface of another kind – in this case, on silicon substrates. The project team studied techniques for growing the material and gained a better understanding of why defects occur in its crystalline structure, and how these affect performance. They were able to overcome a number of technological barriers that previously held back 3C-SiC growth on a larger scale to reduce the number of defects, considerably increasing the materials’ performance and reliability. By developing a process for reducing thermal stress, CHALLENGE succeeded in growing thick 3C-SiC layers of up to 300 microns. “This material has never been grown at these thicknesses before, because the large thermal stress resulted in breakage,” La Via says.
A key added value of the new process lies in the combination of low production cost and high energy efficiency. The main applications of the technology developed under the CHALLENGE project are electric vehicles and solar inverters, which convert the output of solar panels into current that can be fed into the grid. “In both application fields, the adoption of 3C-SiC technology will result in a large reduction of power dissipation, involving considerable environmental benefits,” La Via notes. Electric cars would also see their autonomy improved, as the technology could increase the distance they will travel with the same charge. In the case of large-scale deployment, the impact on climate change mitigation efforts could be huge, La Via says: “With the introduction of 3C-SiC in the power device market, a reduction in carbon dioxide emissions by up to 6 million tons per year could be achieved.” Effectively bringing the technology to the market will require additional research efforts. According to La Via, these should aim to further improve the quality of the material on a number of levels including defect density and stress, and to improve our understanding of the requirements for building efficient devices. The team involved in the CHALLENGE project is currently working on several follow-up initiatives to turn the project’s results into tangible progress.
CHALLENGE, cubic silicon carbide, 3C-SiC, heteroepitaxy, electric cars, solar inverters, power electronic devices, green transition