European supply chain for high-power space electronics
GaN-based power microwave devices have emerged as the technology of choice to operate reliably in the harsh space environment. Semi-insulating SiC is the most suitable substrate for these devices, which are difficult to realise with other semiconductor materials. Due to the absence of an industrial capacity to undertake production of SiC substrates, to date, the European Space Agency (ESA) relies on the United States for the supply of GaN-based components and systems. The EU funded the three-year-long project EUSIC (High quality European GaN-wafer on SiC substrates for space applications) with the aim to establish a purely European supply chain for GaN technology. As part of this project, researchers have developed processes for producing high-quality semi-insulating 3-inch SiC substrates superior to those imported from non-European sources. EUSIC brought together all different parts of the supply chain, a substrate manufacturer, epitaxial growth houses and a monolithic microwave integrated circuit foundry. The project's collaborative character accelerated the development activities, covering crystal growth, wafering, epitaxial growth and the integration of transistor components. A high-electron-mobility transistor was ultimately assembled by metal organic chemical vapour deposition on European-grown semi-insulating SiC substrates. The structure consisted of an isolating buffer and a 22 nm-thick barrier layer with nominally 18 % aluminium and 82 % gallium, and a 3 nm-thick GaN cap. Numerous tests of electrical, morphological and structural properties confirmed the very high quality of the semi-insulating 3-inch SiC substrates, compared to benchmarked 3-inch SiC substrates. Transistor output power parameters of the devices on SiC substrates were also found to be superior to those produced on commercial references substrates. The new supply chain for integrated circuits built using GaN on SiC substrates is expected to trigger innovation in systems manufactured in Europe for communications and remote sensing satellites. EUSIC work will therefore enhance Europe's competitive position in research and innovation.
Keywords
Gallium nitride, space applications, SiC substrates, transistors, EUSIC, semi-insulating
