Method for the Manual Analysis of Moire Structures in STM images

A method is presented to manually determine the lattice parameters of commensurate hexagonal moire structures resolved by STM. It solves the problem that lattice parameters of moire structures usually cannot be determined by inspection of an STM image, so that computer-based analyses are required. The lattice vector of a commensurate moire structure is a sum of integer multiples both of the two basis vectors of the substrate and of the adsorbed layer. The method extracts the two factors with respect to the adsorbed layer from an analysis of the Fourier transform of an STM image. These two factors are related to the two factors with respect to the substrate layer. Using the cell augmentation method, six possible moire structures are identified by algebra. When the orientation and lattice constant of the substrate are roughly known, this information is usually sufficient to determine a unique moire structure and its lattice parameters.

Automated summary

The method presented manual determination of lattice parameters of commensurate hexagonal moire structures resolved by STM through analysis of the Fourier transform of an STM image. By using the cell augmentation method and algebra, six possible moire structures can be identified. When the orientation and lattice constant of the substrate are roughly known, this information is usually sufficient to determine a unique moire structure and its lattice parameters.