Analysis of Anisotropic Ionization Coefficient in Bulk 4H-SiC with Full-Band Monte Carlo Simulation

High-field electron transport characteristics in bulk 4H-SiC are simulated with the full-band Monte Carlo method, and anisotropy of the ionization coefficient alpha is discussed. The simulation results exhibit larger alpha along 11 (2) over bar0 direction than 0001 direction, which is consistent with the experimental observation. Furthermore, the dependence of alpha on the electric field direction theta is investigated. Compared to the existing analytical model, the present simulation results show a steeper increase when theta is tilted from the c-axis, which is originated from the anisotropic nature of the hot-electron heating.