Migration on atomically clean (100) and (111) planes of Ge monocrystals was investigated by using the field emission method. Sealed-off field emission tubes, with a channel multiplier, were used. The surface density of K adatoms on the Ge surfaces was determined by using a standard W crystal plate, which could be moved between the adsorbate atom flux and a low-energy electron gun. The effect of the external electric field upon the surface diffusion of K was studied with the aim of determining the dipole moment of the K adatoms on Ge surfaces. The resultant values of 4.5 and 4.1 Debye, for K adatoms on (100) and (111) Ge planes, respectively, were in good agreement with the initial dipole moments which were deduced from work-function measurements. The effects of the atomic relief and electronic structure of the substrate upon the properties of an alkali adlayer on a semiconductor surface were predicted on the basis of the experimental results.

J.S.Suchorski: Surface Science, 1990, 231[1-2], 130-4