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The increasing global energy demand requires drastic improvements in energy efficiency to meet the requirements for a sustainable development. During the late 1980s, it was demonstrated that power devices based on Silicon (Si) technology are rapidly approaching their theoretical limits, and new alternatives for materials should be considered in the future. In this context, silicon carbide (SiC) semiconductor has emerged as one of the most viable alternative to Si for the next-generation of power devices. In fact, thanks to their physical, electrical and thermal properties, SiC power devices can achieve higher efficiency with respect to the Si counterparts.

The first SiC power MOSFETs appeared on the market in 2011. Nowadays, they are found in a variety of applications in the automotive, photovoltaic and power supply segments, and further market growth is foreseen in the coming years.

The advantages of SiC technology make it desirable also for space and avionics applications. In fact, the higher efficiency of SiC compared to Si, would allow to great reduction in number of power components needed, and therefore in weight, in spacecraft or aircraft PMAD (Power Management and Distribution) systems. This technology is also interesting for applications in particle accelerators, such as the accelerator complex at CERN in Geneva.

Despite the beneficial characteristics of SiC, its adoption in these fields is still hindered by the unexpected susceptibility to the radiation encountered in these applications, which increases the risk of single event effects (SEEs). These effects are a perturbation of the normal operation of the device induced by the radiation, which could ultimately cause a destructive failure of the component.

In this research, Corinna Martinella studied the radiation effects observed in SiC power MOSFETs when exposed to different types of radiation.

“In space, avionics and CERN accelerators SiC power MOSFETs would be exposed to different radiation environments which can induce more or less severe effects. In order to overcome and mitigate this problem, the mechanisms underlying the damage caused by the radiation need to be understood", says Martinella.

Her results contributed to build the model of one particular SEE called “degradation”, which is problematic especially for space applications:

“In space, the interaction of a single ion within the component can cause the destruction of the device. In order to reduce the risk, the device can be de-rated, which means operating the MOSFET at a voltage lower than what it is designed for. This is usually a sufficient procedure in the case of Si components, but for SiC another effect called degradation is observed. In this research, we analysed the physical mechanism of degradation and we managed to identify the sensitive regions of the device which are responsible for this effect”, tells Martinella.

During these years, Corinna Martinella tested several commercial devices with different design, and compared the failure mechanisms for each structure. These analyses provide a wide set of data about the capability of these components to withstand radiation, which is relevant for industry and for the device manufacturers.

“This research provides insights on different effects induced by radiation in SiC power MOSFETs. Ultimately, one of the objectives of the community is to manufacture devices that are less sensitive to radiation and could be safely used in space applications. However, this process can be successful only after having a clear understanding of the physics of failure. With this work, we provided an additional piece of information in this direction”, Martinella sums up.

The research is published in JYU Dissertations series, number 401, Ģ��ֱ��, 2021.
ISSN 2489-9003; 401), ISBN 978-951-39-8726-8 (PDF)
Link to publication: 

M.Sc. Corinna Martinella defends her doctoral dissertation "Single-Event Radiation Effects in Silicon Carbide Power MOSFETs" on Friday 18th of June at the Ģ��ֱ�� starting at noon. Opponent is Dr. Veronique Ferlet-Cavrois (ESA ESTEC, Netherlands) and Custos is Senior Researcher Arto Javanainen (Ģ��ֱ��). The doctoral dissertation is held in English.

The audience can follow the dissertation online.
Link to the Zoom Webinar event (Zoom application or Google Chrome web browser recommended):

Phone number to which the audience can present possible additional questions at the end of the event (to the custos): +358 40 614 6881