Effects of stacking faults on electron transport in 4H-SiC n-type epilayers under unipolar operation evaluated by TCAD simulation

Effects of stacking faults (SFs) on electron transport in 4H-SiC n-type epilayers under unipolar operation were quantitatively investigated by utilizing Technology Computer-Aided Design simulation. Electrical characteristics in a lightly-doped n-type epilayer with a single Shockley-type staking fault (1SSF) were calculated while taking quantum mechanics into account. In the simulation, the 1SSF in the epilayer was modeled by a quantum well for conduction electrons, the bandgap and width of which were determined so as to reproduce experimental photoluminescence results in previous studies. The degradation mechanisms of the unipolar conduction due to the 1SSF were visually demonstrated by profiling the electrostatic potential, and a significant voltage drop in a depletion region of a potential barrier formed by the trapped electrons in the quantum well was clarified; resulting in increased epilayer resistance. Based on the model, temperature and doping dependences of the quantities affected by SFs were also discussed.