VIBRATIONAL CHARACTERIZATION AND ELECTRONIC-PROPERTIES OF LONG RANGE-ORDERED, IDEALLY HYDROGEN-TERMINATED SI(111)

The use of a well defined, long range ordered surface is of fundamental interest for the determination of surface-specific intrinsic physical parameters. Ideally hydrogen terminated Si(111) surfaces are prepared by wet chemical treatment in basic HF solutions. The mechanism of formation is based on preferential etching of defects, leading to an ideal hydrogen terminaison of the (111) plane, without any reconstruction and with a high degree of perfection, Infrared spectroscopy is used to probe the quality of the surfaces by quantifying the extent of the perfect domains. High resolution photoemission spectroscopy of such highly homogeneous surfaces shows exceptional narrow features in both the valence band and the core level regions. The valence band levels and their dispersion are well described by first-principles calculations using a quasi particle self-energy approach within the Heidin's GW approximation. Two surfaces core level states are evidenced, arising from the silicon surface atoms and the backbonds. A crystal field effect splits the surface Si 2P(3/2) component. Their position and relative intensity find a satisfactory agreement with recent calculations using first principles perturbation theory.