A Novel Non-Invasive Cryostatic Spectrometry Technique to Characterize the Carriers’ Multiplication Factor in Silicon Carbide Power Devices

Abstract

The design of robust power semiconductor devices and the assessment of their susceptibility to terrestrial cosmic rays induced failures requires the accurate characterization of the device-internal electric field. This work presents a non-invasive cryostatic spectrometry technique making use of a soft-gamma Am241 radioactive source, to sense the device-internal electric field of silicon carbide power devices, through the measurement of the carriers’ multiplication factor. TCAD and Monte Carlo simulations tools are coupled to predict the soft-gamma irradiation spectra and to localize the hotspots for charge multiplication in the device structure. An empirical relationship is derived to convert the carriers’ multiplication factor measured at cryogenic temperature to the multiplication factor at ambient temperature. Finally, by highlighting the correlation between the multiplication factor and the failure rate of power devices exposed to terrestrial cosmic radiation, the technique is proposed as a complimentary method for the on-field assessment of the Safe-Operating Area.