GROWTH-MORPHOLOGY AND ELECTRONIC-STRUCTURE OF NA FILMS ON SI(111)-(7X7) AND SI(111)-NA(3X1)

The growth of thin Na films on the clean Si(111)-(7 x 7) and the Si(ll l)-Na(3 x 1) reconstructions is investigated using scanning tunnelling microscopy as well as core and valence level photoemission. The growt h morphology as well as the evolving electronic structure of the overl ayer on these different substrates is studied in derail. Tr is shown t hat the Na layer on both surface reconstructions is metallic at satura tion coverage, but the presence of a distinct interfacial layer in a n on-metallic state is demonstrated. (C) 1998 Elsevier Science B.V. All rights reserved.