Abstract
Surfaces of organic ultra-thin films were observed by two different surface sensitive microscopies, metastable electron emission microscopy (MEEM) and photoelectron emission microscopy (PEEM). We describe here our experimental evidence of diffusion of a large organic semiconductor molecule, chloroaluminum phthalocyanine (ClAlPc), on a MoS2 crystal surface. The PEEM and MEEM images showed that a micropattern of ClAlPc ultrathin film prepared on the MoS2 surface by vacuum deposition shrinks with time and finally disappears even at room temperature at which the molecules do not evaporate. As another example, we also show the diffusion of ClAlPc molecules on an oriented monolayer of ClAlPc. These results indicate that control of molecular diffusion is necessary for the preparation of stable micro or nanostructure of organic thin films.
