PHOTOEMISSION INVESTIGATION OF THE INITIAL GROWTH MODE OF CR ON AG(100)

Ultra-thin Cr films (≤ 12 monolayers (ML) on Ag(100)) have been studied by low energy electron diffraction (LEED) and angle-resolved photoemission spectroscopy. The data show that for substrates at room temperature, Cr agglomeration occurs even at coverages as low as 0.5 ML. In particular, this is unambiguously demonstrated by a careful study of the Ag(100) M̄3 surface state intensity, which is proportional to the bare Ag(100) surface area, as a function of Cr coverage, It is found that, at room temperature, about 2.5 ML of Cr must be deposited in order to quench completely the Ag surface state. Valence band photoemission data clearly indicate that epitaxial growth of bcc Cr does take place in the form of islands exposing (100) surfaces. However, both photoemission and LEED show that Cr(100) surfaces prepared in this way, exhibit an important degree of disorder. © 1990 Pergamon Press plc.