Energy Efficient Power Electronics – Gallium Oxide Power Transistors with Record Levels

High-performance electronic components are essential for future communication, for the digital transformation of society and for applications of artificial intelligence.

transistors
Gallium oxide chip with transistor and measuring structures, manufactured at FBH using projection exposure. | © FBH / schurian.com

With as little space as possible, they should be able to achieve ever higher power densities with low energy consumption and thus work more efficiently. Conventional components reach their limits here. As a result, scientists around the world are researching novel materials and components that meet these requirements. The Ferdinand Braun Institute, Leibniz Institute for High Frequency Technology (FBH) has now achieved a breakthrough with transistors based on gallium oxide (ß-Ga 2 O 3 ).

The newly developed ß-Ga 2 O 3 MOSFETs (dt. Metal-oxide-semiconductor field effect transistor) provide a high breakdown voltage with high current conductivity. With 1.8 kilovolts of breakdown voltage and a record output of 155 megawatts per square centimeter, they achieve unique global metrics close to the theoretical material limit of gallium oxide. At the same time, the breakthrough field strengths achieved are far greater than those of established large band gap semiconductors such as silicon carbide or gallium nitride.

Optimized layer structure and gate topology

To achieve these improvements, the FBH team started on the layer structure and the gate topology. The basis was provided by substrates from the Leibniz Institute for Crystal Growth (IKZ) with an optimized epitaxial layer structure. This reduced the defect density and improved the electrical properties. This leads to lower resistances when switched on. The gate is the central “switching point” in field effect transistors, which is controlled by the gate-source voltage. Its topology has been further developed so that the high field strengths at the gate edge could be reduced. This in turn leads to higher breakdown voltages. The detailed results were published on 26.8.2019 online in the September issue of the IEEE Electron Device Letterspublished. Direct to Paper p. 1503 .