DIRECT OBSERVATION OF SIH3 ON A 1-PERCENT-HF-TREATED SI(111) SURFACE BY SCANNING TUNNELING MICROSCOPY

Scanning tunneling microscopy (STM) has been made on an as-prepared Si(111) surface by the 1%-HF treatment. The STM images for both the empty and filled states exhibit regular dots with the threefold symmetry on the flat parts of the surface: the distance between dots measures 2.2 angstrom. The origin of these dots can be ascribed to the H atoms of the trihydride (SiH3) phase on the Si(111) surface. The electrons can tunnel from or to the tail states of the sigma (filled) states or the sigma* (empty) states around the H atoms for the SiH3 radicals, respectively.