Adsorption of metal-phthalocyanine molecules onto the Si(111) surface passivated by 8 doping: Ab initio calculations

摘要

We report first-principles calculations of the energetic stability and electronic properties of metal-phthalocyanine (MPc) molecules (M = Cr, Mn, Fe, Co, Ni, Cu, and Zn) adsorbed on the δ-doped Si(111)-B(3~(1/2) × 3~(1/2) ) reconstructed surface. (ⅰ) It can be seen that CrPc, MnPc, FePc, and CoPc are chemically anchored to the topmost Si atom. (ⅱ) Contrastingly, the binding of the NiPc, CuPc, and ZnPc molecules to the Si(111)-B(3~(1/2) × 3~(1/2)) surface is exclusively ruled by van der Waals interactions, the main implication being that these molecules may diffuse and rearrange to form clusters and/or self-organized structures on this surface. The electronic structure calculations reveal that in point (ⅰ), owing to the formation of the metal-Si covalent bond, the net magnetic moment of the molecule is quenched by 1μ_b, remaining unchanged in point (ⅱ). In particular, the magnetic moment of CuPc (1μ_B) is preserved after adsorption. Finally, we verify that the formation of ZnPc, CuPc, and NiPc molecular (self-assembled) arrangements on the Si(111)-B(3~(1/2) × 3~(1/2)) surface is energetically favorable, in good agreement with recent experimental findings.