Temperature Dependence of Shockley Stacking Fault Expansion and Contraction in 4H-SiC p-i-n Diodes
The nucleation and expansion of Shockley stacking faults (SSFs) in 4H-SiC is known to induce an increase in the forward voltage drop (Vf) of bipolar devices such as pin diodes. However, recent annealing experiments have shown that SSFs can not only expand, but that low temperature annealing (210-7000C) induces a contraction of the SSFs that is coupled with a full and repeatable recovery of the Vf drift. Here we report that following extended periods of forward bias operation that the Vf drift of 10kV 4H-SiC pin diodes saturates, with the saturation Vf drift dropping with increasing stressing temperature. Upon reaching saturation, increases in temperature during forward bias operation at the same injection conditions also lead to a partial recovery of the Vf drift. Furthermore, the magnitude of this current-induced recovery is dependent upon the injection current, as reductions in the current cause a slower, but larger overall Vf drift recovery. All of these results clearly indicate that the current driving force models for SSF expansion are either incomplete or incorrect and that further efforts are required for a more complete understanding of SSF dynamics to be obtained.
Akira Suzuki, Hajime Okumura, Tsunenobu Kimoto, Takashi Fuyuki, Kenji Fukuda and Shin-ichi Nishizawa
J. D. Caldwell et al., "Temperature Dependence of Shockley Stacking Fault Expansion and Contraction in 4H-SiC p-i-n Diodes", Materials Science Forum, Vols. 600-603, pp. 273-278, 2009