Improved initial epitaxial growth of β-FeSi2 on Si(111) substrate by Al-doping

Effects of Al doping on the iron silicide growth were investigated in reactive deposition epitaxy (RDE) on Si(111) substrates epsilon-FeSi(111) layer was grown on the Si(111) substrate when the fe of 50 angstrom was deposited at 750 degrees C. In Al-doped samples grown by co-deposition kof fe and Al, both the crystal orientation of epsilon-FeSi(111)/Si(111) and the surface flatness of the layer were improved with increasing Kundsen-cell temperature of Al (T-Al). The highly-oriented epsilon-FeSi templates were annealed at 850 degrees C for a phase transition from epsilon-FeSi to beta-FeSi2. X-ray diffraction (XRD) measurements of the annealed samples showed that the crystal orientation of beta-FeSi2(202)//Si((111) strongly depended on that of the epsilon-FeSi//Si. In undoped samples, XRD peaks originating from polycrystalline beta-FeSi2 were observed in 20 scan measurements. On the other hand, the peak intensities from the beta-FeSi2 polycrystal became much samall in the Al doped beta-FeSi2 grown at T-Al - 925 degrees C. These results revealed that Al, doping during the RDE growth promotes the epitaxial growth of epsilon-FeSi(111)//Si(111) and the crystallographic orientaion relationshoip between epsilon-FeSi and Si affects the epitaxial growth of beta-FeSi2(101)//Si(110) on Si(111) by the post-annealing. (C) 2008 WILEY-VCH Veriag GmbH & Co. KGaA, Weinheim.