News: Microelectronics
30 April 2025
Fraunhofer IAF presents bidirectional 1200V GaN switch with integrated free-wheeling diodes
At the Power Electronics, Intelligent Motion, Renewable Energy and Energy Management (PCIM 2025) Expo & Conference in Nuremberg (6–8 May), Fraunhofer Institute for Applied Solid State Physics IAF of Freiburg, Germany is presenting results achieved as part of the three-year project ‘GaN4EmoBiL — GaN power semiconductors for electro-mobility and system integration through bidirectional charging’ launched in mid-2023 and funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK).
1200V monolithic bidirectional switch with integrated free-wheeling diodes
Fraunhofer IAF has developed a gallium nitride (GaN) monolithic bidirectional switch (MBDS) with a blocking voltage of 1200V that contains two free-wheeling diodes. The researchers used Fraunhofer IAF’s new GaN-on-insulator technology for manufacturing: highly insulating materials such as silicon carbide (SiC) and sapphire are used as the carrier substrate for the GaN power semiconductor to improve 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 1200V class.
Picture: Monolithic bidirectional 1200V GaN switches (MBDS) with integrated free-wheeling diodes, made at Fraunhofer IAF in a multi-project wafer run using GaN-on-insulator technology (courtesy of Fraunhofer IAF).
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 400V currently dominate the market, but 800V technology is gaining ground. The leap to 1200V has a positive effect on the long-distance capability of electric cars and the utility value of electric trucks.
The 1200V GaN MBDS with integrated peripherals is being presented by Dr Michael Basler at the PCIM Conference on 8 May (10:10–10:30am) in the oral session on GaN Devices II on Stage München 1, based on Basler’s paper ‘Highly-Integrated 1200V GaN-Based Monolithic Bidirectional Switch’ (to 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 multi-level converters with bidirectional switches for blocking voltages up to 48V: Researchers have used a conventional single-gate high-electron-mobility transistor (HEMT) based on a aluminum gallium nitride/gallium nitride (AlGaN/GaN) heterostructure in a low-voltage 3-level T-type converter as a bidirectional switch, achieving simpler control of the transistor than with a bidirectional transistor with two gates for such topologies. Like the 1200V MBDS, this approach enables simpler control in addition to a space-efficient component design.
On 6 May, Daniel Grieshaber is presenting the paper ‘Investigation of a Single-Gate GaN HEMT as Bidirectional Switch in a Low Voltage Multilevel Topology’ at the PCIM Conference Poster Session in the GaN Devices I section (3:30–5pm) in the foyer.
PCIM Expo: GaN power electronics portfolio along the semiconductor value chain
In addition to innovations in bidirectional switches, Fraunhofer IAF is working along the entire semiconductor value chain on materials, components, modules and subsystems for GaN-based power electronics in the voltage classes 48V, 100V, 200V, 600V and 1200V. The current focus is on lateral and vertical components, monolithic integration, and highly insulating substrates such as sapphire or SiC. In addition to the results presented at PCIM 2025, Fraunhofer IAF is already working on components in the 1700V class.
Fraunhofer IAF is presenting an overview of its R&D portfolio in power electronics at the PCIM Expo in Hall 6, booth 260. Exhibits include an epitaxial 8-inch GaN wafer, processed 4-inch GaN-on-SiC and GaN-on-sapphire wafers, GaN power ICs, integrated lateral and vertical GaN components and 600V half-bridge modules based on GaN.
At the PCIM Conference, Dr Richard Reiner is also summarizing Fraunhofer IAF’s latest power electronics developments in the presentation ‘Lateral, Vertical, Bidirectional! Innovations and Progress in GaN Devices and Power ICs’ on 7 May (10:50–11:10am) on the Technology Stage.
Fraunhofer IAF-led GaN4EmoBiL project targets bidirectional charging for EVs
