Simulation of the incomplete ionization of the n-type dopant Phosphorus in 4H-SiC, including screening by free carriers

The simulation of the incomplete ionization of substitutional dopants in Silicon Carbide (SiC) is often performed using Boltzmann statistics and ionization energy values that do not depend on free carrier concentrations. But in the case of heavy doping Fermi-Dirac statistics is needed, while the case of an inhomogeneous dopants distribution or that of an excess carrier injection requires local free carrier concentration-dependent impurity ionization energies. Here a model for describing partial ionization from diluted to high homogeneous doping densities in SiC and in thermal equilibrium is presented and compared with results on Phosphorus doped 4H-SiC.