Wannier-Stark Ladder and Negative Differential Conductance in 4H-SiC
The work deals with the highly important problem of the qualitative temperature dependence of avalanche breakdown voltage in p-n junctions based on 4H-SiC. As it has been shown before, the temperature coefficient of avalanche breakdown voltage (TCABV) is negative in seven SiC polytypes, including 4Н-SiC. This effect has been explained by the Wannier-Stark localization (WSL). It is worth noting that the plane of the investigated p-n junctions coincided with the basal plane (0001). However the current SiC device technology prefers 4H-SiC p-n junction formation on a plane that has 8о disorientation from (0001). This may result in a weakening of the WSL and, correspondingly, in a positive TCABV. This problem has been elucidated in the present paper. The photocurrent of 4H-SiC p-n junctions in a strong electric field has been scrutinized, that has allowed to discover a negative differential conductivity region and it has testified to the WSL process and negative TCABV.
Robert P. Devaty, David J. Larkin and Stephen E. Saddow
V. I. Sankin and R. Yakimova, "Wannier-Stark Ladder and Negative Differential Conductance in 4H-SiC", Materials Science Forum, Vols. 527-529, pp. 707-710, 2006