Growth related distribution of secondary phase inclusions in 6H-SiC singlecrystals

The formation of grown in defects like misoriented regions and micropipes i s correlated with second phase inclusions such as silicon droplets or carbo n particles. Crystals up to 35 mm diameter were grown on the silicon face b y the modified Lely method. Inclusions could be identified as carbon partic les by SEM and EELS. Their distribution along the growth direction and at t he phase boundary were investigated by optical microscopy. It was found tha t their density varies in axial as well as radial direction. The dependency of the carbon particle concentration on growth parameters such as seed tem perature, time, pressure and the distance between source and seed is shown. A concentration model will be discussed. Therefore any change of the vapor phase composition characterized by the loss of silicon and caused by chang ing of a growth parameter may result in a drastic local increase of the car bon particle concentration. If a critical value is exceeded the lattice inf ormation of the substrate is lost and defects may be formed. (C) 2001 Elsev ier Science B.V. All rights reserved.