Vertical bonding distances and interfacial band structure of PTCDA on a Sn-Ag surface alloy

Abstract

Molecular materials enable a vast variety of functionalities for novel electronic and spintronic devices. The unique possibility to alter or substitute organic molecules or metallic substrates offers the opportunity to modify and optimize interfacial properties for almost any desired field of application. For this reason, we extend the successful approach to control molecular interfaces by surface alloying. We present a comprehensive characterization of the structural and electronic properties of the interface formed between the prototypical molecule PTCDA and a Sn-Ag surface alloy grown on an Ag(111) single crystal surface. We monitor the changes of adsorption height of the surface alloy atoms and electronic valence band structure upon adsorption of one layer of PTCDA using the normal incidence x-ray standing wave technique in combination with momentum-resolved photoelectron spectroscopy. We find that the vertical buckling and the surface band structure of the SnAg${}_2$ surface alloy is not altered by the adsorption of one layer of PTCDA, in contrast to our recent study of PTCDA on a PbAg${}_2$ surface alloy [Phys. Rev. Lett. 117, 096805 (2016)] . In addition, the vertical adsorption geometry of PTCDA and the interfacial energy level alignment indicate the absence of any chemical interaction between the molecule and the surface alloy. We attribute the different interactions at these PTCDA/surface alloy interfaces to the presence or absence of local $\sigma$-bonds between the PTCDA oxygen atoms and the surface atoms. Combining our findings with results from literature, we are able to propose an empiric rule for engineering the surface band structure of alloys by adsorption of organic molecules.

References in corpus (6)

• Giant Spin-splitting in the Bi/Ag(111) Surface Alloy
• The Structural Influence on the Rashba-type Spin-Splitting in Surface Alloys
• Interface dipoles of organic molecules on Ag(111) in hybrid density-functional theory
• Hybrid Interface States and Spin Polarization at Ferromagnetic Metal-Organic Heterojunctions: Interface Engineering for Efficient Spin Injection in Organic Spintronics
• Energy Shift and Wavefunction Overlap of Metal-Organic Interface-States
• Tuning independently Fermi energy and spin splitting in Rashba systems: Ternary surface alloys on Ag(111)

Cited by in corpus (1)

• Atomic and mesoscopic structure of Dy-based surface alloys on noble metals