GROWTH OF CR ON AG(001) STUDIED BY SCANNING-TUNNELING-MICROSCOPY

The growth of ultrathin films of Cr on Ag(001) was studied for deposit ion temperatures between 285 and 440 K. Film formation was characteris ed by Scanning Tunneling Microscopy (STM), Auger Electron Spectroscopy (AES) and Low Energy Electron Diffraction (LEED). At room temperature , sub-monolayer deposition results in the formation of irregular monol ayer islands. Histogram analysis shows two distinct island heights, on e close to the estimated height for a chromium layer on Ag(001) (0.156 nm) and the other close to the Ag(001) layer height (0.205 nm). Compa ct multi-layer islands are also observed. Higher, broader islands form with increasing deposition temperature. These islands preferentially nucleate on the upper terraces close to descending step edges. The dat a do not support reports of metastable monolayer growth close to 440 K . (C) 1997 Elsevier Science B.V.