Scientists at the Ferdinand-Braun-Institut (FBH) have achieved what they believe is a breakthrough for transistors based on the ultra wideband semiconductor gallium oxide (ß-Ga2O3). They published their results in IEEE Electron Device Letters.
The newly developed ß-Ga2O3-MOSFETs provide a high breakdown voltage of 1.8kV and a record power figure of merit of 155 MW/cm2.
These performance figures are close to the theoretical material limit of Ga2O3. At the same time, the breakdown field strengths achieved are significantly higher than those of established wide bandgap semiconductors such as SiC or GaN.
In order to achieve these improvements, the FBH team tackled the 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 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 to reduce high field strengths at the gate edge. This in turn to higher breakdown voltages. The detailed results were published online on August 26, 2019 in the ‘Lateral 1.8 kV β -Ga2O3 MOSFET With 155 MW/cm2 Power Figure of Merit‘ by Kornelius Tetzner et al; IEEE Electron Device Letters (Volume: 40 , Issue: 9 , Sept. 2019 )