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

Abstract

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.

Limited current conduction due to various types of stacking faults in n-type 4H-SiC epilayers

“…[16][17][18][19] The mechanism of the decline in current conduction due to SFs are qualitatively explained based on a quantum well (QW) model. [20][21][22][23] The SF forms a QW in the conduction band where the electrons are trapped and accumulated, and consequently the trapped electrons induce a potential barrier in the conduction band, which disturbs the electron current flow. However, the impacts of the SFs on current conduction in the SiC epilayers have not been quantitatively and experimentally clarified because multiple SFs partially intercept the active area of the device in most cases.…”

“…Our previous study showed that a potential barrier in the conduction band due to the SF-originated QW limits electron current flow considerably because only the electrons surpassing the potential barrier can contribute to the current flow. 23) Accordingly, the experimental correlation between the smaller forward current conductance and the longer SForiginated PL peaks is attributed to a higher potential barrier evoked by a deeper QW, which traps more electrons.…”