Investigation of the Nucleation Process During the Initial Stage of PVT Growth of 4H-SiC

Due to high growth temperatures during the physical vapor transport (PVT) it is still almost impossible to gain proper insight into the actual growth conditions. Therefore, computer tomography (CT) is used as an in-situ monitoring during the crystal growth process. With the help of this technique, it is possible to observe the nucleation centers during the initial stage of growth (CT after 0 h) of a 4H-SiC single crystal. These growth islands are likely formed before the actual growth conditions are reached. Raman investigations of the area around a growth island located directly on the interface between seed and grown crystal is used to support this assumption. In addition, optical analysis after KOH etching were made to reveal the defects around the growth island. The island exhibits a inhomogeneous doping concentration in comparison to the surrounding grown crystal.