PHOTOEMISSION-STUDY OF NA GROWTH ON THE SI(100)C(4X2) SURFACE AT LOW-TEMPERATURE

Na adsorption on the Si(100)c(4 x 2) surface has been studied at low t emperature with photoelectron spectroscopy. Spectra from the valance b and and from the Si 2p and Na 2p core-levels were recorded at similar to 120 K for increasing Na coverage. The development of the Na 2p spec tra from the interface layer and from the bulk and surface of the Na g rowing on the interface was followed as function of the coverage. The valence band features of the room temperature saturated Si(100)2 x 1-N a surface remain throughout the coverage range studied here. The main change with coverage is the increasing emission from an extra structur e at the Fermi-level. The line shape of the Si 2p spectra is essential ly unchanged except that it becomes broader and the spectra get attenu ated with increasing Na coverage. A systematic analysis of the photoel ectron spectra combined with the results of low-energy electron diffra ction lead to the conclusion that Na grows in a Stranski-Krastanov mod e on the cold Si(100)c(4 x 2) surface. (C) 1997 Elsevier Science B.V.