CLEAN SI(110) - A SURFACE WITH INTRINSIC OR EXTRINSIC DEFECTS

Clean surfaces of n-type, low doped silicon samples cut along the (I 1 0) plane or along properly chosen vicinal ones have been studied by lo w energy electron diffraction, Auger electron spectroscopy and photoem ission yield spectroscopy. Several procedures, combining treatments bo th outside and inside the ultrahigh vacuum chamber, have been used to get the smoothest and cleanest surfaces. It is found that the surface always contains a high density of structural defects as proved by the LEED measurements and by the work function and the tail of filled surf ace states in the gap. Compared results between nominal and vicinal (1 10) surface show the dominance of intrinsic (like along the Si(111)(7 x 7) reconstructed surface) over extrinsic (poor preparation procedure s) defects.