Electric vehicles have reached the performance threshold.
And a team of scientists has made significant progress in exploring ways to significantly improve the design of silicon carbide power supplies that are intended for use in electric vehicles, trains and many other vehicles, according to a recent study. published in the journal Physical condition Solidi (b).
When they are placed on the market, this could significantly increase the range, productivity and energy efficiency of all-electric vehicles.
Improving the productivity, size and energy consumption of electric vehicles
Silicon carbide (SiC) unipolar semiconductors have gained widespread commercial use, but to work with them, we encounter Catch-22 between a specific resistor at turn-on or breakdown voltage and a specific drift resistance. So the researchers looked at something called a super-junction structure, which means the arrangement of the “n and p layers” inside the excavations in the drift layer, which allows bipolar operation in such devices. And this opens a door to go beyond the unipolar limit.
And in a recent study, researchers based in Japan investigated depth distribution defects found in SiC bipolar diodes created by aluminum doping (Al doping). Al doping involves either epitaxial or ion implantation, the first of which requires layer-by-layer deposition of semiconductor materials on substrate material. Ion implantation, on the other hand, requires you to bombard the layers of semiconductor material with charged high-energy particles. But ion implantation can create defects embedded deep in the semiconductor layers, potentially leading to negative effects on conduction modulation that can disrupt performance.
And in studying how and when this happens, researchers are exploring the “engineering space” for solutions that will significantly improve EV performance. “Our findings will help optimally design SiC power supplies that will soon be used in electric vehicles, trains, etc.,” said Associate Professor Masashi Kato of the Nagoya Institute of Technology, Japan, who led the recent study in a press release. with IE by email. “These results will ultimately help improve productivity as well as the size and energy consumption of traction systems in vehicles and trains. To further investigate the defect depth distribution, the research team created two SiC PiN diodes using Al-doped p-layers.
The low power consumption of SiC power supplies will be crucial for future vehicles
One of the diodes is made by epitaxial growth and the other by ion implantation. They then assessed the distribution of defects in both diodes using conventional “deep level transient spectroscopy” (DLTS), which allowed them to examine their properties with cathodoluminescence (CL). And the research team found that the deposition of the p-type layer by epitaxial growth did not leave additional damage in the adjacent n-type layers. Although this was promising, the same epitaxially grown diode also showed a slight instability that caused the formation of defects at a deep level. In addition, the specific resistance of this diode was low due to the effects of conductivity modulation, overcoming one of the two main obstacles described above.
On the other side of the experimental spectrum, the researchers found that the doping of Al in the diode created by ion implantation managed to reach a high specific resistance without change in conductivity modulation. The researchers also noticed that the defects in the semiconductor device penetrated at least 20 micrometers (µm) from the implantation area. “Our study shows that ion implantation in SiC bipolar devices is needed[s] to be processed at least 20 µm from the active regions “, said Kato in the message shared with IE. It is the low energy consumption found in SiC power supplies that will become crucial for future vehicles as the effects of climate change worsen everything that happens wrong in the world, thanks in large part to the fossil fuel industry. But by advancing semiconductor technology at unprecedented speeds, we could reduce the security of humanity and other species on Earth and make a more sustainable future a reality much sooner than current estimates expect.