The Impact of Temperature and Switching Rate on the Dynamic Characteristics of Silicon Carbide Schottky Barrier Diodes and MOSFETs

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Abstract
Silicon carbide Schottky barrier diodes (SiC-SBDs) are prone to electromagnetic oscillations in the output characteristics. The oscillation frequency, peak voltage overshoot, and damping are shown to depend on the ambient temperature and the metal-oxide- semiconductor field-effect transistor (MOSFET) switching rate (dI DS /dt). In this paper, it is shown experimentally and theoretically that dI DS /dt increases with temperature for a given gate resistance during MOSFET turn-on and reduces with increasing temperature during turn-off. As a result, the oscillation frequency and peak voltage overshoot of the SiC-SBD increases with temperature during diode turn-off. This temperature dependence of the diode ringing reduces at higher dI DS /dt and increases at lower dI DS /dt. It is also shown that the rate of change of dIDS/dt with temperature (d 2 I DS /dtdT) is strongly dependent on R G and using fundamental device physics equations, this behavior is predictable. The dependence of the switching energy on dI DS /dt and temperature in 1.2-kV SiC-SBDs is measured over a wide temperature range (-75 °C to 200 °C). The diode switching energy analysis shows that the losses at low dI DS /dt are dominated by the transient duration and losses at high dI DS /dt are dominated by electromagnetic oscillations. The model developed and results obtained are important for predicting electromagnetic interference, reliability, and losses in SiC MOSFET/SBDs.
Funding Information
  • Engineering and Physical Science Research Council (EPSRC)
  • Power Electronics Devices Theme

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