The Cryogenic Testing and Characterisation of SiC Diodes

High-resolution cryogenic performance testing is carried out on 4H-SiC PiN and Schottky diodes. At 2K intervals from 20 to 320K, current-voltage tests are performed to extract static characteristics such as turn-on, ideality factor and barrier height from across the temperature range. We also analyse the performance of the diodes within a low current/voltage switching circuit across the same temperature range using an inductive switching setup. Both diodes suffer markedly increased conduction losses at the lower temperatures, the PiN diode losing all the benefits of conductivity modulation as dopant freezes-out, reducing its series resistance. However, minor gains in the total switching losses are expected at low temperature due to faster switching speeds.