Crystal and electronic structure engineering of epitaxial silicene

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Silicene on ZrB2(0001) thin films grown on Si(111) is a perfect test bench for the study of this two-dimensional material, which only exists in epitaxial forms. We particularly investigated (i) the local origin of the electronic states of silicene and (ii) how the properties of silicene can be tuned upon adsorption of foreign atoms. Our study revealed the microscopic origin of the previously resolved pi states and pointed out a clear correlation between the local conformation of the Si atoms and the contribution of their pz orbital to those states. Upon adsorption of potassium atoms, we found out that there is no change in the silicene structure and that an electron donation to silicene occurs. It also causes the hybridization between ZrB2(0001) surface state and silicene pi states, which are decoupled in the pristine case. The investigation of the hydrogenation of silicene suggests that a capping layer forms without affecting significantly the internal structure of silicene.