Observation of Initial Growth Stage of Amorphous Si Film Deposited on 7×7 Superlattice Surface of Si(111) by Low-Energy Electron Diffraction

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Abstract
The intensities of low-energy electron diffraction (LEED) were measured from Si films with various thicknesses (d) which had been deposited on a 7×7 reconstructed surface of Si(111) substrates maintained at 170°C. The intensity profile from Si films at d>60 Å gives a feature showing the formation of an amorphous phase. From ultrathin Si films with 5 Å<d<60 Å, two peaks were observed clearly at positions which correspond to the (0, 0) and (1, 0) rods in the Si(111) surface. This suggests that the Si film in the vicinity of the Si(111) substrate comprises interface layers with the some ordered structure. Some discussion is given on the interface layers, which are composed of two epitaxially grown grains. A normal stacking sequence of the diamond structure is formed in one grain and the reversed stacking sequence grows at the stacking fault layer on the preserved 7×7 structure in another grain.