GaN on silicon carbide wafers

If successful, the pay-offs from GREAT² will be great indeed. More capable satellites broadcasting stronger signals, coupled with improved ground terminals could extend two-way connectivity to trains, planes, cars and almost all corners of Earth.

Also, the improved materials and processing knowledge gained from GREAT² should boost Europe’s knowhow and ability to produce devices capable of operating in harsh environments. A new generation of GaN-based sensors could function without bulky shielding and operate everywhere, from the close proximity to the Sun envisaged for ESA’s Solar Orbiter mission to the radiation-soaked Jupiter system, the planned destination of a joint ESA–NASA orbiter.

The aim is to have a foundry process for space-ready microwave discrete transistors and MMICs/integrated circuits by 2011–12, with an in-orbit demonstration potentially as early as 2013.

There will be other benefits beyond the space sector, Mr Barnes concludes: “If larger silicon carbide wafers become available at affordable cost or if industry goes down the silicon substrate route, then I see no reason why GaN would not completely displace gallium arsenide. It would encompass everything from solar cells to lasers, in particular boosting the efficiency of power converters, which is a massive market, and be highly beneficial for the environment.”

Funding and coordination with other European projects

GREAT² is being funded through ESA’s Basic Technology Research Programme (TRP) and the General Support Technology Programme (GSTP), with a larger GaN development envisaged through GSTP, the Advanced Research in Telecommunications Research (ARTES) programme and national funding.

In addition to ESA-funded activities, the Agency is coordinating GaN development with the European Commission (EC) and the European Defence Agency. The first outcome of this coordination was the launch of a complementary EC-funded Seventh Framework Programme (FP7) project, under the FP7 Strengthening Space Foundations theme, entitled ‘Advanced GaN Packaging’ (AGAPAC).

The aim of AGAPAC is to develop high thermal-dissipation packages that can be used to assemble power transistors and MMICs so that the full performance potential of GaN can be realised for space. Further complementary activities are planned; in 2009 proposals for related research, such as on substrate developments, were submitted in response to the second call of the FP7 space theme and are being evaluated.