ANISOTROPY IN SURFACE-DIFFUSION OF GA ATOMS ON A GE(001) PLANE AT THE APEX OF A FIELD-EMISSION TIP

The surface diffusion coefficient of Ga atoms in a (001) plane on a Ge tip was measured by an autocorrelation analysis of field-emission intensity fluctuations. Anisotropy of the surface diffusion for the [110] and [110BAR] directions was observed at a specific part of the (001) area of the tip surface. The ratios of the anisotropy in the surface diffusion coefficients ranged from 1.2 to 2.5 depending on the coverage and temperature. The activation energy for the direction of the fastest diffusion was 1.2 eV at the coverages of 0.2 and 0.3 monolayers. and was 0.1 eV higher for the direction of the slowest diffusion.