Study on Dislocation Behaviors during PVT Growth of 4H-SiC

The generation and transformation of dislocations in 4H-SiC crystals grown by PVT were investigated. Experiments were carried out in two stages for more comprehensive observation on dislocation behaviors. For the first stage known as initial growth, we investigated mainly the seed and grown interface. The behavior and transition of the dislocations in grown crystal were observed along the length of the crystal at second stage. The formation of threading edge dislocations (TEDs) strongly depends on the surface morphologies related with internal temperature gradients during crystal growth. The basal plane dislocation (BPDs) and threading screw dislocation (TSDs) cause from the seed crystal and formed at the initial stage of growth were gradually decreased in number along the length of the crystal and under certain conditions such as distorted stresses, dislocations were converted into other types of dislocations.