THE SURFACE-DIFFUSION OF GE ATOMS ON TUNGSTEN IN STRONG ELECTRIC-FIELDS

Field emission microscope has been used to study the effect of strong electric field F on the surface diffusion energy Q of germanium on tun gsten in the direction (121) --> (100) at various adsorbate concentrat ion Theta. It was found that Q is a linear function of the external fi eld F at all investigated concentrations, although the slope of the de pendences Q(F) changes drastically at Theta --> 1. This behavior can b e explained by taking into account the double layer capacity. At minor concentrations the germanium atoms show the effective dipole moment o f a positive sign that can be considered as a result of the electron d ensity concentration on the bond between adatom and substrate.