Silicon Carbide Diodes
Silicon carbide power diodes were specifically designed for the protection of solar cell arrays in solar panels mounted on satellites and space exploration modules. The first batches of devices are currently being used for two European Space Agency missions: BepiColombo and Solar Orbiter.
These diodes, developed by CSIC with the collaboration of ALTER TECHNOLOGY (ATN), have the peculiarity of an unusually wide operating temperature range, from -170oC up to 300oC, which is possible thanks to the use of silicon carbide instead of silicon as bare material. Silicon carbide is a so-called wide bandgap semiconductor, and presents superior electrical and physical characteristics to silicon, making it particularly suitable for high power, high temperature and high frequency electronic applications. Silicon carbide is currently used in power electronics applications such as hybrid and electric cars, renewable energies, power supplies, train transportation, but in a standard operating temperature range from -40oC up to 175oC.
In addition to the use of silicon carbide as semiconductor material for high temperatures, a specific and robust processing and packaging technology has been developed. The internal device structure differs from standard commercial SiC diodes. The interconnections and the package have been optimised specifically for the semiconductor die to take full benefit of SiC's intrinsic performance. ATN was responsible for the electrical, environmental and reliability test campaigns. The feedback from ATN studies helped to optimise the final design and fabrication process of the device. As the operating range of these devices was unusual, no characterisation standards were available, and adaptation of current ESA ESCC standards was performed by ATN and ESA specialists. A specific screening and qualification campaign has been designed and performed. This can be used as a baseline for the future definition of novel high temperature device test standards.
This device is the first Spanish component included in the European Space Agency European Preferred Part List (EPPL). However, the diodes could be used in other high temperature applications.
Space-qualified silicon carbide power diodes have been developed by the CNM-CSIC power group in Barcelona in close collaboration with ATN, and produced by D+T Microelectrónica in the CNM-CSIC large scale facility (ICTS), and qualified by the ALTER TECHNOLOGY Optoelectronics and New Technologies division in Tres Cantos (Madrid). From now on, these parts will be handled as an ALTER TECHNOLOGY specific product for high reliability and harsh environment-related markets.