Anisotropic drift diffusion model for 4H-, 6H-SiC devices simulation

In this paper, a CAD tool based on the drift-diffusion model was developed to simulate and compare the anisotropic behavior of 4H- and 6H-SiC hexagonal crystal polytypes used for device applications. The tool adopts a tensor formalism to describe the anisotropic nature that influence the dielectric permittivity constant, and both the electron and hole mobility constants. It also addresses the temperature dependence of all considered physical quantities such as the band gap, and takes into account SRH and Auger recombination, and incomplete ionization of dopants as well. Simulations have been performed for each prototype for the electric field parallel and orthogonal to the c-axis of the crystal, and a well set of values has been extracted from the I-V characteristics to show how the anisotropy may influence the electrostatic potential and the current density.