Gallium oxide power transistors said to achieve record values

Researchers from Germany’s Ferdinand-Braun-Institut (FBH) have made a breakthrough in their development of transistors based on gallium oxide (ß-Ga₂O₃), achieving high breakdown voltage combined with high current conductivity.

Powerful electronic components are indispensable for future communications, for the digital transformation of society and for artificial intelligence applications. On a footprint as small as possible, they should offer low energy consumption and achieve ever higher power densities, thus working more efficiently. This is where conventional devices reach their limits.

Scientists all over the world are thus investigating new materials and components that can meet the above requirements — and FBH’s Ga₂O₃-MOSFETs (metal-oxide-semiconductor field-effect transistors) may just have succeeded.

Writing in the journal IEEE Electron Device Letters, the team recounted how they tackled layer structure and gate topology. The basis was provided by substrates from the Leibniz Institute for Crystal Growth with an optimised epitaxial layer structure. As a result, the defect density could be reduced and electrical properties improved. This leads to lower on-state resistances.

The gate is the central ‘switching point’ of field effect transistors, controlled by the gate-source voltage. Its topology has been further optimised, allowing for high field strengths to be reduced at the gate edge. This in turn leads to higher breakdown voltages.

With a breakdown voltage of 1.8 kV and what is said to be a record power figure of merit of 155 MW/cm², the transistors achieve performance figures close to the theoretical material limit of gallium oxide. At the same time, the breakdown field strengths achieved are significantly higher than those of established wide-bandgap semiconductors such as silicon carbide or gallium nitride.

Image caption: A gallium oxide chip with transistor structures and structures for measurement purposes, manufactured at FBH using projection lithography. Image ©FBH/schurian.com

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