A consortium project led by Germany’s Ferdinand-Braun-Institut and funded by the European Space Agency (ESA) is working to develop Ka-band gallium nitride (GaN) monolithic microwave integrated circuits (MMICs), with potential applications in satellite and radar technology.
The Kassiopeia project, which launched this month, aims to deliver a fully independent value-added supply chain using technology which is currently only accessible in Europe. The consortium, consisting of Ferdinand-Braun-Institut, the University of Bristol in the UK and Swedish GaN-on-SiC materials provider SweGaN, will produce individual advanced semiconductor components such as silicon carbide (SiC) substrates; GaN epitaxy and device processing; and larger devices including power amplifiers. In order to demonstrate the potential of this supply chain, the project will produce GaN MMICs operating on the Ka-band frequency, the section of the microwave segment of the electromagnetic spectrum with frequencies ranging between 26.5GHz and 40GHz.
Reproducible and reliable
“The unique selling point of our GaN MMIC technology is its highly reproducible and reliable iridium sputter-gate technology,” said Dr Joachim Würfl, head of the Power Electronics department at Ferdinand-Braun-Institut. “This technique reduces dynamic losses through gate lagging to values up to two times less than competing institutional and industrial technologies.”
The project is able to benefit from sector-leading technologies developed at Ferdinand-Braun-Institut, including industry-compatible MMICs developed on 100mm GaN-on-SiC wafers, which have been shown to significantly improve the reliability of devices; as well as novel approaches to circuit concepts and process technology aimed at reducing parasitic energy losses. Meanwhile, researchers at the University of Bristol are focusing primarily on conducting direct thermal measurements on active GaN transistors – these will be performed using micro-Raman thermography techniques and advanced modelling of the devices’ key characteristics.
Innovation and improvement
SweGaN, whose contribution to the project is funded by Rymdstyrelsen, the Swedish national space agency, will provide semi-insulated SiC substrates for evaluation; as well as sharing specialist knowledge of epitaxial layer design and optimisation. “We are excited to participate in this ESA-aligned project, together with Ferdinand-Braun-Institut and the University of Bristol,” commented SweGaN founder and CTO Jr-Tai Chen. “Conventional GaN-on-SiC materials for Ka-band applications still lack maturity, leaving significant room for innovation and improvement. SweGaN will introduce its revolutionary epitaxial manufacturing process to address the challenge.”
The Kassiopeia initiative is funded through the ESA’s Advanced Research in Telecommunications Systems (ARTES) ‘European Ka-band high power solid-state technology for active antennas’ advanced technology programme. The benefits to device performance and reliability incurred by the MMIC development could be particularly significant in terms of improving technology used in spaceborne projects.
