Europhys. Lett, 35 (3), pp. 215-220 (1996)
Hydrogen-induced semimetal-semiconductor transition of two-dimensional detected by electron energy loss spectroscopy
T. Angot, J. J. Koulmann and G. Gewinner
Laboratoire de Physique et de Spectroscopie Electronique, URA CNRS 1435, Faculté des Sciences et Techniques - 4, rue des Frères Lumière, 68093 Mulhouse Cedex, France
(received 14 March 1996; accepted in final form 5 June 1996)
PACS. 71.30 - Metal-insulator transitions.
PACS. 79.20Kz - Other electron-impact emission phenomena.
PACS. 73.20Mf - Collective excitations (including plasmons and other charge-density excitations).
Abstract:Using high-resolution electron energy loss spectroscopy, we find that two-dimensional silicide epitaxially grown on Si(111) undergoes a semimetal-semiconductor transition upon atomic H dosing. Passivation of the Si top layer already inferred from previous photoemission work is directly demonstrated and provides further evidence of the similarity between the silicide surface atomic structure and the ideal Si(111) termination. Nevertheless, in contrast with the latter case it is shown by using simple chemical bonding and electron counting arguments that saturation of the Si dangling bonds cannot explain by itself the semiconducting nature of the hydrogenated silicide. Possible mechanisms that might account for the observed transition are discussed.
Copyright EDP Sciences