Adsorption and thermal stability of 1,4 benzenedimethanethiol on InP(110)

Self-assembly of dithiol molecules is of interest because these can be used as linkers between metallic or semiconductor entities and thus employed in molecular electronics and plasmonic applications, or for building complex heterostructures. Here we focus on dithiol self-assembly by evaporation in vacuum, a method that could circumvent the dithiol oxidation that can occur in solution. We present a high resolution X-ray photoelectron spectroscopy (XPS) and an ion scattering study of adsorption and desorption of 1,4-benzenedimethanethiol on InP(110) as a function of exposure and sample temperature. Results for InP are compared to those on Au(111) and found to differ due to formation of a thick BDMT layer at room temperature, resulting from extra molecules sticking on top of the self-assembled monolayer. This may play an adverse effect in some afore-mentioned applications as in molecular electronics. We furthermore study the evolution of the dithiol film with sample temperature and the elements remaining at the surface after annealing and delineate initial coverage dependent effects.