Strained MxSi1-x(M=Fe, Mn) layer on virtual substrate: growth, morphology Yuanmin Shao, and Zuimin Jiang Phys. Dept., Fudan Univ., Shanghai, People’s Republic of China Motivation Si-based dilute magnetic semiconductors (DMSs) are regarded as promising function materials for spintronics. Strain could be used to ajust the distance between impurities and Si atoms in DMSs so as to change the their magnetism. Therefore, it is worth investigating the correlation among the strain, microstructures and physical properties of the films. I. Fabrication of GexSi1-x virtual substrate Raman spectra Growth conditions AFM height image excitation wavelength: 325nm excitation wavelength: 514nm Si-Si (substrate) Si-Si Si-Si (GexSi1-x) 300nm GexSi1-x @550℃ Ge 20% Ge 30% Ge-Si Ge-Si 250nm LT-Si buffer @450℃ Si (001) 10 μ m× 10 μm 10 μ m× 10 μm Ge-Si Ge-Si Roughness: 0.67nm RMS: 0.85nm Roughness: 1.37nm RMS: 1.82nm A low temperature (LT) Si buffer layer was first grown on Si (001) substrates at 450℃ to reduce the threading dislocation density in the SiGe layer. Then a GexSi1-x films was grown on the top of the LT Si buffer at 550℃. Smooth surfaces with no straight crosshatch lines were fabricated and we are able to keep the surface roughness of Ge0.2Si0.8 layer under 1 nm. From the positions of Ge-Si peaks and Si-Si peaks with the 325nm radiation, the GeSi strain relaxation of the Ge0.2Si0.8 sample surface was determined to be 98%, while that of the Ge0.3Si0.7 sample was 89%. II. Fabrication of strained MxSi1-x(M=Fe, Mn) layer on Ge0.2Si0.8 Virtual Substrate Raman spectra Growth conditions Unstrained MnxSi1-x layer FexSi1-x layer Strained MnxSi1-x layer strained unstrained Si-Si (511.9) Si-Si (518.5) 2nm Si 2nm Si Si-Si (520.7) excitation wavelength: 325nm excitation wavelength: 325nm excitation wavelength: 325nm 10nm MxSi1-x 10nm MxSi1-x ×9 ×9 10nm Ge0.2Si0.8 10nm Si MnSi1.73 MnSi amorphous Si 10nm MxSi1-x MnSi1.73 10nm MnxSi1-x 300nm Ge0.2Si0.8 @550℃ MnSi 300nm LT-Si buffer @450℃ Si-Si (516.3) 300nm LT-Si buffer @450℃ Si substrate amorphous Si Si substrate The MnxSi1-x multilayers were grown at 200 ℃ and then in-situ annealed at 400 ℃. From the Raman spectra of as-grown sample, we find MnSi phase has formed before the crystallization of Si. With the annealing temperature rising to 600 ℃, Si was crystallized and MnSi phase changed into MnSi1.73 phase. Furthermore, even in the unstrained sample, we could still find the Si-Si peak deviating from 520.7 cm-1, which suggests the Mn-Si alloys introduced tensile strain in Si. The FexSi1-x multilayers were grown at 400 ℃. However, no Fe-Si phases were found in Fe doped Si multilayers. On the top of Ge0.2Si0.8 virtual substrate, strained and unstrained M doped Si multilayers were grown. III. Conclusions Smooth GexSi1-x virtual substrates were frabricated on Si (001) substrate. The microstructures of strained and unstrained multilayers were determined by Raman spectra. No Fe-Si alloys were found to form at the grown temperature of 400 ℃. However, in MnxSi1-x multilayers, MnSi was found to form before the crystallization of Si, which is harmful to the formation of DMSs. Furthermore, the crystallization of MnSi1.73 would introduce extra tensile strain in crystal Si.