Project to develop aluminium nitride AlN power transistors and system designs

Technology News |
By Nick Flaherty

The €3.3m “Power transistors based on AlN (ForMikro-LeitBAN)” project is coordinated by the Ferdinand-Braun-Institut for highest frequency technologies in Berlin and will run until 2023.

In Europe alone, it is estimated that more than three terawatt hours of energy are lost each year in the conversion of electrical energy – for example when converting the mains voltage to the low DC voltage for the operation of electronic circuits. The “ForMikro-LeitBAN” project is researching technological measures to further increase efficiency and thus conserve resources. This requires efficient switching power semiconductors that enable a high energy density. If they were used on a large scale, energy savings would be noticeable and make a relevant contribution to CO2 reduction.

The project aims to develop AlN as a new wide bandgap semiconductor material for this task, test it on suitable components and qualify it for future applications in systems. This is because conventional silicon-based power components are making it increasingly difficult to increase the efficiency of electrical converters and power amplifiers. New semiconductor materials with improved properties must therefore be researched and brought to market maturity.  AlN has so far been little researched for electronic applications, offers up to 10,000 times less transmission loss than silicon components.

It is also characterized by very high breakdown voltage resistance and thermal conductivity – ideal prerequisites for power semiconductors with high energy density and efficiency. Freestanding insulating AlN wafers are to be used and qualified as a material basis. Compared to an AlN epitaxy on foreign substrates such as silicon carbide, the dislocation density can be reduced by five orders of magnitude. This offers the potential for fast and efficient switching components with high reliability at the same time.

The new AlN devices are based conceptually on gallium nitride (GaN) technology, but the transition from conventional foreign substrates such as silicon carbide, sapphire or silicon to free-standing AlN substrates is new. ForMikro-LeitBAN researches the development of such AlN wafers and tests them in a specially tailored component process. Test systems for millimeter wave applications and for power electronic energy converters qualify the new highly efficient AlN components for applications in corresponding systems. They are preparing the transfer of this technology into an industrial environment. This is planned as part of a follow-up project. An industrial advisory board supports the work in the consortium: Infineon for power electronics, UMS for millimeter wave technology and III/V-Reclaim for the recycling of AlN wafers.

The partners involved in ForMikro-LeitBAN jointly cover the entire value chain from wafers to power electronic systems. Fraunhofer IISB in Erlangen contributes know-how for AlN crystal growing and wafer production, while TU Bergakademie-Freiberg (IAP) develops process module development and analysis for the technology. The Technical University Cottbus-Senftenberg is developing millimeter wave systems as part of the project, and TI Berlin is participating with power-electronic systems based on the devices.

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