Anisotropy in breakdown field of 4H–SiC

The breakdown fields along the $\text{〈112̄0〉}$ and $\text{〈033̄8〉}$ directions in 4H–SiC have been measured. For the measurements, epitaxial $p^{+}n$ diodes with mesa structures were fabricated on the $\text{(112̄0)}$ and $\text{(033̄8)}$ faces, and they showed good rectification properties and avalanche breakdown. The breakdown fields along these directions calculated from the breakdown voltage were found to be about three quarters of that along the $\text{〈0001〉}$ direction in 4H–SiC. The cause of the anisotropy in breakdown field is discussed.