Determine the origin of periodic modulations at graphene nanoribbon boundaries

Determine whether the periodic scanning-tunneling-microscopy contrast modulations observed near nanoribbon-like graphene boundaries on Ge(001) arise from edge-induced quantum interference, a structural superlattice such as a strain-distorted moiré pattern, or a combination of these mechanisms.

Background

Scanning tunneling microscopy reveals periodic contrast modulations with an approximate 0.5 nm length scale near the boundaries of nanoribbon-like graphene regions on Ge(001). The modulation could result from edge-induced quantum interference associated with intervalley backscattering, but local lattice distortions, possible stacked graphene layers, strain, lattice relaxation, and out-of-plane corrugation also make a structurally distorted moiré superlattice plausible. The available measurements do not resolve which mechanism, or combination of mechanisms, is responsible.

References

However, the present data do not allow this mechanism to be distinguished unambiguously from a structural superlattice. In particular, the local lattice distortions visible in the atomic-resolution images and the possible presence of locally stacked graphene layers make a strain-distorted moiré pattern another plausible interpretation.

— Electronic Coupling and Charge-Transfer Landscape of Graphene on Ge(001)/Si(001): Multiscale Analysis Assisted by Machine Learning  (2609.37827 - Dabrowski et al., 29 Sep 2026) in Section 2.2, paragraph discussing Figure 5f