STM AND AFM STUDY OF THE ADSORPTION OF EP-PTCDI MOLECULES ON SI(111) 7X7

LAURA N. SERKOVIC LOLI, J. ESTEBAN GAYONE, ESTEBAN A. SÁNCHEZ, OSCAR GRIZZI, AND VLADIMIR A. ESAULOV

Congreso; 10th Inter-American Congress of Electron Microscopy; 2009

(EP-PTCDI) on Si(111) 7x7 under UHV conditions has been studied by means of variable temperature Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM). The Si(111) surface was prepared on its 7x7 reconstruction by the method of flash annealing and then cooled down to room temperature by the STM cryostat to speed up thermal stabilization.By means of STM, we observed for low coverage, that at room temperature and at 150ºC the molecules adsorbed isolated on different adsorption sites without preferential adsorption on silicon steps or defects, and without formation of ordered islands as in the case of Ag(111). For medium doses we observe agglomeration of molecules without any defined order. The post annealing of the sample up to 500ºC was not enough to promote the rearrangement of the molecules on the surface but their decomposition.For much higher coverage (film thickness of ~20nm) we used the AFM working in air instead of the STM because of the semiconductor characteristic of the film. We observed that the molecules formed 3D islands leaving part of the silicon substrate uncovered.