The formation of grown in defects like misoriented regions and micropipes is correlated with second phase inclusions such as silicon droplets or carbon particles. Crystals up to 35 mm diameter were grown on the silicon face by the modified Lely method. Inclusions could be identified as carbon particles by SEM and EELS. Their distribution along the growth direction and at the phase boundary were investigated by optical microscopy. It was found that their density varies in axial as well as radial direction. The dependency of the carbon particle concentration on growth parameters such as seed temperature, 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 changing of a growth parameter may result in a drastic local increase of the carbon particle concentration. If a critical value is exceeded the lattice information of the substrate is lost and defects may be formed.