PEEM and SEM studies of In/PTCDA/MoS 2 system: an evidence of anisotropic surface diffusion of In atoms

Abstract

A diffusion-induced changes of indium microstructure was observed by photoelectron emission microscopy (PEEM) and scanning electron microscopy (SEM) for evaporated microstructure of In metal on a pelylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) thin film on MoS 2 substrate. The PEEM and SEM images show a periodic triangle pattern, although deposited shape of the In microstructure was square. In contrast such an unusual images originating from anisotropic diffusion was not observed when deposition metals or substrate materials were changed. These results suggest that the peculiar phenomenon originates from (1) chemical reaction between PTCDA and In, and (2) the molecular packing structure which depends on substrate materials.