Silicene on Monolayer PtSe₂: From Strong to Weak Binding via NH₃ Intercalation

We study the properties of silicene on monolayer PtSe₂ by first-principles calculations and demonstrate a much stronger interlayer interaction than previously reported for silicene on other semiconducting substrates. This fact opens the possibility of a direct growth. A band gap of 165 meV results from inversion symmetry breaking and large spin-splittings in the valence and conduction bands from proximity to monolayer PtSe₂ and its strong spin-orbit coupling. It is also shown that the interlayer interaction can be effectively reduced by intercalating NH₃ molecules between silicene and monolayer PtSe₂ without inducing charge transfer or defect states near the Fermi energy. A small NH₃ diffusion barrier makes intercalation a viable experimental approach to control the interlayer interaction.