Reaction pathway analysis for the contraction of 4H-SiC partial-dislocations pair in the vicinity of surface

Abstract

In order to reduce harmful dislocations in the 4H-SiC substrate, the improvement technique of basal plane dislocation-threading edge dislocation (BPD-TED) conversion ratio has been investigated. In this paper, we have investigated the effect of surface on the contraction of partial-dislocations pair using reaction pathway analysis and molecular dynamics to clarify the mechanism of the BPD-TED conversion. It is found that the contraction of the partial-dislocation parallel to the surface occurs if the distance from the surface is less than 0.25 nm. As for the partial-dislocations intersected to the surface, the dislocation segment which is located less than 0.25 nm below the surface is easily contracted. Depending on the direction of the Burgers vector, step slightly increase/decrease the energy barrier. Since the cross slip of the perfect screw dislocation easily occurs in the vicinity of the surface, the BPD-TED conversion is controlled by the contraction of partial-dislocations located less than 0.25 nm below the surface.