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Characterization of the susceptibility to cosmic radiation of wide bandgap power devices by radioactive sources and at cryogenic temperatures

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The use of exempt radioactive sources to characterize the internal electric field of silicon power devices has been proven in I. This solution allows to observe impact ionization under operating conditions but may be invasive and requires the opening of the device package. The use of techniques with a low degree of invasiveness is still under investigation, with particular interest on the exploitation of gamma emitters.

Due to the leakage current at ambient temperature and the low charge deposition of gamma radiation in semiconductor devices, the charge deposition induced signal may be completely indistinguishable from the noise. To obtain a better signal-to-noise ratio the noise contribution of the device under test (DUT), acting as a detector, must be limited. A possible solution is to carry out measurements at cryogenic temperatures.

Short Description

The increase of the leakage current with increased reverse bias in power devices has an exponential dependency on temperature. As the leakage current of the detector is the main limiting factor for the sensitivity of the measurement setup, its decrease would allow an overall better SNR, even when the charge deposited by the incident radiation is small, such in the case of gamma radiation.

A significant reduction of the leakage current is obtained taking the detecting device to cryogenic temperatures. The work consists in the design of a measurement setup that allows to operate the DUT at low temperatures and its exploitation to characterize the internal electric fields of wide bandgap power devices.


A measurement setup for cryogenic temperatures must be designed and implemented.

• Get acquainted with the electronics for spectrometry
• Get acquainted with the existing spectrometer
• Review literature and investigate possible solutions
• Implement and test the new solution
• Demonstration for the characterization of power devices susceptibility to cosmic radiation.


• None

Status: Available

• Looking for interested students.
• Contact: Dr. Mauro Ciappa Marco Pocaterra
• -> ETHZ IIS H.78


Dr. Mauro Ciappa
Marco Pocaterra


Mathieu Luisier

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