Time resolved determination of electrical field distributions within dynamically biased power devices by spectral EBIC investigations

Time resolved investigations of electric field distributions in the near-surface regions of a dynamically biased power device using spectral EBIC microscopy are introduced. The technique described provides a facility for determination of local electrical field strengths inside devices by factoring out induced currents in their spectral components. A developed setup enhances the signal to noise ratio and reduces disturbing signals up to 160 dB, offering consequently a possibility for EBIC analysis at high switching currents of the DUT. Quantitative E-field distributions at steady state device biasing conditions and variations of the field during reverse and forward recoveries are shown under operating conditions for the example of a power diode with a guard ring as a field termination structure.