Homoepitaxial growth experiments were done in a horizontal hot wall CVD reactor without rotation of the substrate, conceptually described in detail byHenry et al., 13  using SiH4 and C2H4 as Si- respectively C-precursors diluted in a hydrogen carrier gas flow of 50 l/min with HCl or HBr as growth additives and no intentional dopants added to the gas mixture.