Simple models of hydrogen adsorption on germanium

The dependence of work function Δφ on degree of coverage Θ for the Ge(100) and Ge(111) surfaces determined in terms of simple models that include the dipole-dipole interaction of hydrogen adatoms. It is found that experimental dependence Δφ(Θ) for the Ge(111) surface can be explained by taking into account an increase in the adsorption bond length with Θ. The charge of the adatoms as a function of Θ is calculated, and the variation of the surface conductivity of the substrate is estimated.