Pattern of Near-Uniform Avalanche Breakdown in Off-Oriented 4H SiC

A streaky emission pattern was observed for near-uniform avalanche breakdown in large-area high-voltage p-n diodes in off-oriented 4H SiC. The streaks originate from unilateral expansion of microplasmas in the direction of the C-axis inclination. The unilateral expansion of avalanche plasma is attributed to anisotropy of high-field carrier transport in 4H SiC. At a high current density, the plasma streaks coalesce to form continuous plasma region over the entire area of the high-power device.