Joint Project "ForMikro-GoNext" Driving Gallium Oxide for Vertical Power Semiconductors

Galliumoxid-Chip mit Transistor- und Messstrukturen, hergestellt am FBH mittels Projektionsbelichtung.
Gallium oxide chip with lateral transistors, manufactured at FBH by projection lithography. "ForMikro-GoNext" aims at a vertical device architecture.

The ForMikro-GoNext joint project examines beta-gallium oxide. Participants include the Leibniz Institute for Crystal Growth, the Ferdinand Braun Institute, the University of Bremen as well as ABB and Aixtron. The project is funded by the BMBF with some 2 million euros for a period of four years.

New semiconductor materials with wide bandgap such as silicon carbide (SiC) and gallium nitride (GaN) achieve a higher breakdown field strength compared to silicon. As a result, devices can be built much smaller. But in comparison to SiC and GaN, beta-gallium oxide (β-Ga2O3) has more than twice the breakdown field strength and thus the potential to even further increase the efficiency of power converters equipped with such devices. High voltages can be switched with significantly less material – the basis for even more compact systems.

In addition, transistors based on β-Ga2O3 are characterized by a low on-resistance at a given breakdown voltage and faster switching transients, which leads to even lower power losses. Due to these properties, that material has the best prerequisites to become the high-performance material for next generation power applications. At the end of August 2019, we reported that the Ferdinand Braun Institute (FBH) was able to manufacture such a lateral MOSFET capable of 155 MW/cm².

ForMikro-GoNext aims to use the high breakdown field strength of β-Ga2O3 even more efficiently by using a vertical component structure. By improving the use of the chip area, it is also possible to scale the devices more easily to larger, technically relevant switching currents. The development of such transistors requires an adapted process chain from crystal growth through epitaxy and device processing to characterization, which is completely covered within the project.

By pooling the expertise of the Leibniz Institutes IKZ (gallium oxide crystal growth, epitaxy and material characterization) and FBH (device design, manufacturing and testing) it is expected to efficiently transfer the achieved results from basic research into application- and industry-oriented research. The Institute for Electrical Drives, Power Electronics and Devices (IALB) at the University of Bremen provides qualified assessment of the application potential of the new devices with its power electronic characterization capabilities. Reliability tests will provide information about the stability of the Ga2O3 transistors. The project will be supported by industrial partners ABB Power Grids Switzerland and Aixtron – Aixtron in the field of epitaxy, ABB in the design and testing of the devices.