Epitaxial Growth of SixGe1−x Films on Si by Solid Phase Epitaxy.

It has been demonstrated in the literature that amorphous Si (or Ge) can be transported across a metal layer and grown epitaxially on Si(Ge) single crystal substrates in the solid phase. The objective of this study is to investigate if amorphous SixGe1−x mixtures can be transported uniformly across a medium and grown epitaxially on single crystal substrates without phase separation. The samples were prepared by e-beam evaporation of thin Pd films onto Si<100> substrates, followed by co-evaporation of SixGe1−x alloyed films (0<x<1) without breaking vacuum. The samples were anneaie in vacuum at 300°C to form a Pd silicide-germanide layer at the interface, then at 500°C for transport of the alloyed layer across the Pd silicide-germanide layer and subsequent epitaxial growth on Si substrate. The samples were investigated by x-ray diffraction and by MeV ion backscattering and channeling. The results show the alloyed film transports uniformly with no phase separation detected. The channeling result shows the grown alloyed layer is epitaxial with some Pd trapped in the layer. This simple technique is potentially useful for forming lattice-matched non-alloyed ohmic contacts on III–V ternary and quaternary compounds.