Origin analysis of expanded stacking faults by applying forward current to 4H-SiC p–i–n diodes

Abstract

Stacking faults expanded by the application of forward current to 4H-SiC p–i–n diodes were observed using a transmission electron microscope to investigate the expansion origin. It was experimentally confirmed that long-zonal-shaped stacking faults expanded from basal-plane dislocations converted into threading edge dislocations. In addition, stacking fault expansion clearly penetrated into the substrate to a greater depth than the dislocation conversion point. This downward expansion of stacking faults strongly depends on the degree of high-density minority carrier injection.

Influence of basal-plane dislocation structures on expansion of single Shockley-type stacking faults in forward-current degradation of 4H-SiC p–i–n diodes

“…We investigated the dependence of the origin of the expanded 1SSF on the stress current applied to 4H-SiC p-i-n diodes. 22) In this paper, we present these experimental results in more detail and discuss the relationship between stress-current density and the 1SSF expansion origin.…”

“…12,13,19) In our previous study, the original area of 1SSFs expanded by applying forward current to 4H-SiC p-i-n diodes was observed by transmission electron microscopy (TEM) with high spatial resolution. 20) TEM observation has clarified that 1SSF expands into the substrate when high-density minority carriers are injected into the substrate. This means that although the BPD-TED conversion is effective in suppressing BPDs in the epitaxial layer, other techniques, such as inserting a recombinationenhanced layer at the interface between the epitaxial layer and the substrate, are necessary to reduce the density of minority carriers injected into BPDs in the substrate.…”

Relationship between depth of basal-plane dislocations and expanded stacking faults by application of forward current to 4H–SiC p-i-n diodes

“…[2][3][4][5] Among these defects, basal-plane dislocation (BPD) is known to be the origin of forward-current degradation in 4H-SiC bipolar devices. [6][7][8][9][10][11][12][13][14][15][16] A BPD is composed of two parallel Shockley partial dislocations (PDs) and a single Shockley-type stacking fault (1SSF) on the basal plane. [13][14][15][16] Under forward-current operation of 4H-SiC bipolar devices, minority carriers are injected into a drift layer and recombine with majority carriers.…”

“…[6][7][8][9][10][11][12][13][14][15][16] A BPD is composed of two parallel Shockley partial dislocations (PDs) and a single Shockley-type stacking fault (1SSF) on the basal plane. [13][14][15][16] Under forward-current operation of 4H-SiC bipolar devices, minority carriers are injected into a drift layer and recombine with majority carriers. A Si-core PD constituting a BPD migrates due to the electron-hole recombination energy, which results in 1SSF expansion.…”

“…A Si-core PD constituting a BPD migrates due to the electron-hole recombination energy, which results in 1SSF expansion. 10,[13][14][15][16] This phenomenon increases the resistance of SiC power devices and results in an increase of the on-voltage. [10][11][12][13] Therefore, a reduction in the number of BPDs is very important to ensure the long-term reliability of SiC power devices.…”