Surface diffusion of dysprosium on stepped surfaces of tungsten microcrystal

The mobility of W atoms of the (3 2 0) and (2 2 1) regions of the W microcrystal surface with the tip curvature radius ∼300 nm and the surface diffusion of Dy at average coverage ∼0.1 ML on these regions were investigated by spectral analysis of field emission current fluctuations in the temperature range 500-800 K. The diffusion appears to be one-dimensional for the W(3 2 0) regions and two-dimensional for the W(2 2 1). The surface-diffusion coefficients were determined by comparison of the experimental results with the theoretical spectral density functions derived by Gesley and Swanson. The surface-diffusion parameters were calculated. The results are discussed from the aspect of substrate structure.