Evolution of Threading Edge Dislocations at Earlier Stages of PVT Growth for 4H-SiC Single Crystals

Dislocation structures at the seed/grown-crystal interface in PVT-grown 4H-SiC crystals are investigated. The dislocation density is found to show a sharp increase at the interface and its main contribution is probably ascribable to TEDs which stem from BPDs generating at the interface through the structural transformation. Intense TEM observations reveal an intriguing in-plane distribution structure of the interface BPDs; the BPDs form a two-dimensional dislocation network comprising of {-1100} partial dislocations associated with expanded areas of stacking faults at the nodes of the network.