Origin of the R(15 x 3) surface reconstruction of carburized W(110) - revisited

Abstract

The identification of the surface atomic structure having a large unit cell remains a major challenge, while this surface structure is the starting point for templated growth on it. The atomic structure of the carbon-induced R(15 x 3)-W(110) is investigated by scanning tunneling microscopy (STM) operated around 80 K in near-contact mode, combined with the first-principles calculations. It is shown that the R(15 x 3) reconstruction results from the moire pattern, which a W-C bilayer of alpha-W2C(0001) forms with the W(110) substrate, confirming art earlier prediction by Bauer et al. Besides the moire pattern, the present structure contains the surface lattice deformation, the main ingredient of the other model, and provides a comprehensive picture, well reconciling the two previous models.