Impact of step edges on W(001) surface reconstruction

Abstract

Step edges on the W(001) surface can inhibit the reconstruction of the surface at low temperatures. However, the range of this inhibition, an important parameter for theoretical consideration, has been a matter of controversy. In this paper, we report our study on the impact of step edges on both the clean surface and H-induced reconstructions on the monotonically stepped W(001) surfaces using low-energy electron diffraction. First, the spread of the terrace widths which manifests itself as the broadening of the individual splitting beams from two high-density stepped W(001) surfaces (29- and 36-Å average terrace widths) was obtained by quantitative analysis of the angular intensity distribution of the splitting beams. The spread was found to be ∼13 Å for both stepped surfaces assuming a Gaussian terrace width distribution. Second, based on the spread of the terrace width and an assumed inhibition range the reconstruction domain size distributions were obtained by comparing the calculated and measured angular profiles of the superlattice beams (which do not split due to the random antiphase relationship among the domains) from both surfaces. The deduced inhibition range was 8±2 Å for both clean and H-induced reconstruction surfaces. These results contradict the findings of King and of Bauer and co-worker who suggested a long-range (≥20 Å) inhibition. Possible explanations of the discrepancy will be presented.