Effects of random impurities on two-dimensional island growth in a chemisorbed overlayer

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Abstract
Adsorption of oxygen on a W(112) surface leads to (2×1) superlattice structure. At room temperature, two-dimensional (2D) oxygen islands of (2×1) structure are created at very low coverage. As the coverage increases, the islands grow and coalesce with the possibility of forming either antiphase boundaries or larger islands. Using high-resolution low-energy electron diffraction, we have examined the effects of preadsorbed nitrogen (<5% monolayer) on the island in both equilibrium state and dynamical growth by monitoring the angular profile and peak intensity of the superlattice beam. We found that nitrogen atoms distributed randomly on the surface, which not only limited the size of the 2D oxygen islands but also slowed down the dynamics of the island growth. The implication of these findings to recent intense theoretical discussions on low-dimension random-field Ising model is presented.

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