Mechanism of Hydrogen-driven Free-electron Generation in Silicon Elucidated for First Time Ever

TOKYO--(BUSINESS WIRE)--Mitsubishi Electric Corporation, Institute of Science Tokyo, University of Tsukuba, and Quemix Corporation announced today that they have achieved the world’s first elucidation of how hydrogen produces free electrons through the interaction with certain defects in silicon. The achievement has the potential to improve how insulated gate bipolar transistors (IGBTs) are designed and manufactured, making them more efficient and reducing their power loss. It is also expected to open up possibilities for future devices using ultra-wide bandgap (UWBG) materials.

In the global drive toward carbon neutrality, efforts to make power electronics more efficient and energy-saving are accelerating worldwide. IGBTs are key components responsible for power conversion, so improving their efficiency is a major priority. While hydrogen ion implantation has been used for about half a century to control electron concentration in silicon, the underlying mechanism has remained unclear until now.

In 2023, Mitsubishi Electric and University of Tsukuba jointly discovered a defect complex in silicon that contributes to increasing electron concentration. They confirmed that this complex is formed when an interstitial silicon pair and hydrogen bind, but the reason why free electrons are newly generated in this process was still unclear. By using advanced computational calculations, the four organizations have now uncovered how hydrogen exists inside the defect complex. They have also explained why hydrogen releases electrons and how these electrons become free within silicon. Furthermore, their findings suggest that this mechanism could also be applied to diamond, a promising material for future power semiconductors that is difficult to control in terms of electron levels.

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