Assessing the film-substrate interaction in germania films on reconstructed Au(111)

Abstract

Purely amorphous germania bilayer films are grown on a reconstructed Au(111) surface. The presence of the film affects the native configuration of the Au soliton walls, as observed with scanning tunneling microscopy. They partly avoid the film islands, and partly penetrate under film patches. This behavior indicates a weaker filmsubstrate interaction than the one reported for other oxide films on reconstructed Au(111). Moreover, this new system highlights the impact of the metal support on the structure of ultrathin films of germania: With decreasing film-substrate interaction the amorphous phase is promoted. Density functional theory calculations confirm and rationalize the experimental observations. This work provides a useful generalization of the relationship between film structure and adhesion energy.

Growth and Atomic‐Scale Characterization of Ultrathin Silica and Germania Films: The Crucial Role of the Metal Support

“…The germania bilayer film on Au(111) shows a small adhesion energy, a large interfacial distance and low charge transfer, in comparison to other germania bilayer films (see Table 4). A similar interfacial distance (0.312 nm) has been calculated for a NaCl bilayer film supported on Au(111), an ideal physisorbed film [122, 123, 120, 20] . Moreover, similar adhesion properties are observed for SiO 2 /Pt(111), in agreement with the structural similarities.…”

“…Moreover, this system highlights the impact of the metal–support on the structure of ultrathin films of germania and silica: With decreasing film–substrate interaction the propensity to form the amorphous phase of these glass forming materials increases. DFT calculations confirm and rationalize the experimental observations [20] …”

“…The present report compares the atomic network structure of the two new 2D materials, ultrathin silica and germania films, and highlights similarities and differences between these two glass systems [21, 5, 17–20] . Silica and germania films with a thickness ranging from a monolayer to a bilayer, involve the three atomic‐scale configurations shown schematically in Figure 1.…”

“…When the film–substrate interaction diminishes, purely amorphous germania bilayer films are expected to grow. A pertinent example is the growth of an amorphous germania bilayer film on a herringbone reconstructed Au(111) surface, [20] and references therein. The presence of the film affects the native configuration of the fcc and hcp stacking of the reconstructed Au(111) top layer atoms, [121] as observed with STM (see Figure 6 d).…”

“…To obtain a more general picture of 2D glasses, ultrathin germania films have been successfully synthesized and characterized at the atomic scale on Ru(0001), [17, 18] Pt(111), [19] and Au(111) [20] . These metal supports exhibit different lattice constants and significantly different chemical reactivities, so that each of them promotes the formation of different germania polymorphs.…”