MODIFICATION OF HF-TREATED SILICON (100) SURFACES BY SCANNING TUNNELING MICROSCOPY IN AIR UNDER IMAGING CONDITIONS

The modification of HF-etched silicon (100) surface with a scanning tunneling microscope (STM) operated in air is studied for the first time in samples subjected to the standard HF etching without the follow-up rinsing in H2O. The modifications are produced in air under normal STM imaging conditions (V(t) = - 1.4 V and I(t) = 2 nA). The simultaneous acquisition of topographical, current image tunneling spectroscopy and local barrier-height images clearly shows that the nature of the modification is not only topographical but also chemical. The features produced with a resolution better than 25 nm are attributed to a tip-induced oxidation enhanced by the presence of fluorine on the surface.