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

Abstract

The origin of expanded single Shockley-type stacking faults in forward-current degradation of 4H-SiC p-i-n diodes was investigated by the stresscurrent test. At a stress-current density lower than 25 A cm %2 , triangular stacking faults were formed from basal-plane dislocations in the epitaxial layer. At a stress-current density higher than 350 A cm %2, both triangular and long-zone-shaped stacking faults were formed from basal-plane dislocations that converted into threading edge dislocations near the interface between the epitaxial layer and the substrate. In addition, the conversion depth of basal-plane dislocations that expanded into the stacking fault was inside the substrate deeper than the interface. These results indicate that the conversion depth of basal-plane dislocations strongly affects the threshold stress-current density at which the expansion of stacking faults occurs.

Origin and Generation Process of a Triangular Single Shockley Stacking Fault Expanding from the Surface Side in 4H-SiC PIN Diodes

“…The 1SSFs of T1 and T3 had a right-angled corner on the right side, and these two types are the most frequently observed and repo rted. 3,[5][6][7][9][10][11][12][13][14]16,[19][20][21][22] However, the 1SSFs of T2 had a triangular shape with a right-and-left in contrast to T1 and T3. The expansion direction of T2, which was from the surface to the substrate/epilayer interface, was opposite to that of T3.…”

“…Additionally, it is reasonable that the J th of this BPD at a depth of 1.3 μm was not low but rather an intermediate value, because it has been reported that the J th is related to the depth of the BPD. 19 To confirm the core species directly and to determine the unique Burgers vectors of the PDs that make up the 1SSF, cross-sectional STEM analysis was employed, and the FIB sampling point and observation direction were selected, as indicated by the orange line and arrow in Fig. 4a.…”

“…7 In addition, many analyses have been conducted of these 1SSFs, including current/temperature stress testing, [8][9][10][11][12][13][14] calculations, [15][16][17][18] and crystal analysis. [19][20][21][22][23] The BPD detection by photoluminescence (PL) imaging and the use of a buffer layer between the substrate and the epitaxial layer was proposed as a method for controlling 1SSF expansion 4,7,11,24 with the aim of solving the V F degradation issue.…”

Suppression of stacking-fault expansion in 4H-SiC PiN diodes using proton implantation to solve bipolar degradation

“…In recent SiC epitaxial wafers, BPDs are mostly present in the substrates but not in the epilayers, owing to the conversion of BPDs to TEDs in the initial stage of epitaxial growth 20 – 24 . Therefore, a remaining issue for bipolar degradation is the expansion of BPDs in substrates 25 – 27 . Inserting a “recombination enhancing layer” between a drift layer and a substrate has been suggested as an effective method to suppress the expansion of BPDs in the substrate 28 – 31 .…”

Suppression of stacking-fault expansion in 4H-SiC PiN diodes using proton implantation to solve bipolar degradation

“…[20][21][22][23][24] Therefore, a remaining issue for bipolar degradation is the expansion of BPDs in substrates. [25][26][27] Inserting a "recombination enhancing layer" between a drift layer and a substrate has been suggested as an effective method to suppress the expansion of BPDs in the substrate. [28][29][30][31] This layer enhances the recombination probability of electronhole pairs in the epitaxial layer and decreases the number of electron-hole pairs at the BPDs in the SiC substrate.…”