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Abstract:
The step structure and terrace distribution of Si(001) vicinal surfaces has been studied by profile analysis of the (00) spot and by measuring superstructure spot intensities using high-resolution LEED on a lens-shaped sample. In the [110] azimuth, the transition from single layer (S-) steps at low miscut angle y to double layer (D-) steps occurs continuously between about 2° and 6δ. Beyond 11°, (115) facets are admixed. While the surface in the range 5° ⩽ γ ⩽ 7.5° in all azimuths is built up by (001) terraces separated by steps, an increasing disorder of the edge pattern is deduced when leaving the [110] azimuth. In the range where the surface in the [110] azimuth is not yet single-domain (y = 5°), this decrease starts at a deviation of about ± 10° from the [110] azimuth, for y = 6° and 7.5°, the intensity decreases immediately. In the [100] azimuth, the existence of long-range ordered S-steps with broad terrace width distribution is deduced from the data.
