1200 V GaN switch enables bidirectional current flow with integrated free-wheeling diodes

Technological innovations in power electronics are not only essential for the success of the energy transition, they also provide sustainable support for economic development in Europe. The Fraunhofer Institute for Applied Solid State Physics IAF develops power electronic components based on the wide-bandgap compound semiconductor gallium nitride (GaN) to enable further developments in electric mobility, the energy industry, and climate technology.

Most recently, Fraunhofer IAF has made significant progress in high-voltage and low-voltage components: At PCIM Europe 2025, researchers will present a highly integrated bidirectional switch (MBDS) with a blocking voltage of 1200 V. They will also demonstrate the use of a conventional GaN transistor with a gate contact as a bidirectional switch in a 3-level T-type converter. Both results were achieved as part of the GaN4EmoBiL project.

Efficient power electronics support energy transition and stimulate economic growth

“Geopolitical challenges such as the current tariff conflicts are an opportunity for European economies to gain technological advantages in the key areas of energy generation and mobility by developing their own solutions in power electronics,” emphasizes Achim Lösch, Business Developer for High Frequency and Power Electronics at Fraunhofer IAF.

“The added value of innovative power electronics is obvious: Achieving more power, better efficiency, and greater compactness at the same time advances the relevant technologies of the future: Electric cars charge faster and energy from renewable sources can be converted and stored more efficiently. At Fraunhofer IAF, we are working intensively to provide positive impetus in these important areas through innovative GaN-based components,” explains Lösch.

Bidirectional 1200 V GaN switch (MBDS) with integrated free-wheeling diodes

Researchers at Fraunhofer IAF have developed a GaN MBDS suitable for the 1200 V voltage class with integrated free-wheeling diodes and successfully integrated it into their own GaN technology. The researchers used the new GaN-on-insulator technology of Fraunhofer IAF for the manufacturing: Highly insulating materials such as silicon carbide (SiC) and sapphire are used as the carrier substrate for the GaN power semiconductor to improve the insulation between the components and increase the breakdown voltage.

The MBDS blocks voltage and conducts current in two directions, which saves chip space and reduces conduction losses as there is only one split depletion region. The GaN MBDS can be used in grid-connected power converters for energy generation and storage as well as electric drive systems. In these applications, the MBDS enables the development of systems in the 1200 V class.

Developers are working intensively on electric vehicles in this voltage class as increasing blocking voltages offer significant advantages in terms of everyday usability: Charging power increases and energy losses during operation decrease as a result of lower resistance. Electric cars with 400 V currently dominate the market, but 800 V technology is gaining ground. The leap to 1200 V has a positive effect on the long-distance capability of electric cars and the utility value of electric trucks.

The 1200 V GaN MBDS with integrated peripherals will be presented by Dr. Michael Basler at the PCIM Conference on May 8 from 10:10 to 10:30 a.m. in the oral session on GaN Devices II on Stage München 1. It is based on Basler’s paper “Highly-Integrated 1200 V GaN-Based Monolithic Bidirectional Switch,” which will be published in conjunction with PCIM 2025.

Single-gate GaN HEMT as bidirectional switch in the low-voltage range

Fraunhofer IAF has also made progress in the field of multi-level converters with bidirectional switches for blocking voltages up to 48 V: Researchers have used a conventional single-gate HEMT (high electron mobility transistor) based on the aluminum gallium nitride/gallium nitride (AlGaN/GaN) compound semiconductor heterostructure in a low-voltage 3-level T-type converter as a bidirectional switch, thereby achieving simpler control of the transistor than with a bidirectional transistor with two gates for such topologies. Like the 1200 V MBDS, this innovative approach enables simpler control in addition to a space-efficient component design.

On May 6, Daniel Grieshaber will present the results shown in his paper “Investigation of a Single-Gate GaN HEMT as Bidirectional Switch in a Low Voltage Multilevel Topology” at the PCIM Conference.

Provided by
Fraunhofer Institute for Applied Solid State Physics