Adsorption of Methyl-Substituted Benzylazide on Si(001): Reaction Channels and Final Configurations

The reaction of a methyl-substituted benzylazide on the silicon (001) surface was investigated by means of X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and density functional theory (DFT)-based computations. It was found that the reaction takes place via an intermediate state, which could be experimentally observed at low temperatures. XPS analysis showed that at temperatures of 150 K and above, the azide further reacts on the silicon surface via abstraction of N₂. The final state sees the remaining nitrogen atom of the adsorbate binding covalently to the surface. In the STM images, this final state is associated with two different adsorption configurations. In comparison with DFT calculations, these two configurations are assigned to the molecule being bound via the nitrogen atom only and to a configuration with the molecule bound to the substrate via the nitrogen atom and carbon ring simultaneously.