PTCDA film formation on Si(111):H-1×1 surface: total current spectroscopy monitoring

The process of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) film formation on the Si(111):H-1×1 surface was studied by means of total current spectroscopy (TCS) and low-energy electron diffraction (LEED). Film deposition was performed under ultrahigh vacuum (UHV) conditions at room temperature. Analysis of the evolution of total current (TC) spectra, combined with average film thickness measurements performed by atomic force microscopy (AFM), revealed island growth under the given experimental conditions. This growth type is the result of a very weak interaction between PTCDA molecules and the passivated silicon surface. A preliminary explanation for the fine structure in the TC spectra is given in terms of variation of the elastic electron reflection on the edges of empty electronic bands located above the vacuum level of PTCDA.