Changes in the electronic properties of the Si(100) surface, when a multilayer structure of oxidized Gd atoms is created on it, have been studied, by using the electron spectroscopy methods. It is shown that, after a number of adsorption cycles of Gd and oxygen atoms on the Si(100)-2 × 1 surface at room temperature and the annealing of the obtained structure at 600 ∘ C, the work function decreases from 4.8 to less than 1 eV. The work function reduction at larger numbers of processing cycles is shown to be accompanied by the oxidation of Gd and Si atoms and a gradual decrease of the Si concentration in the near-surface region. The obtained results are explained by the formation of an O-Gd dipole layer on the surface.

Electronic and emission properties of photocathodes fabricated on the basis of multilayered structures of oxidized Gd atoms deposited on the Si(100) surface and additionally covered with fresh layers of Gd atoms have been studied as functions of the structure holding time under vacuum, by using the methods of photoelectron (ℎ = 1.9÷10.2 eV) and Auger electron spectroscopies. It is found that, although the photocathode work function is equal to about 0.5 eV at some research stages, the photoemission is registered only at ℎ ≥ 2.8 eV. The analysis of the results allowed us to propose a model for the energy structure of the photocathode that agrees with experimental data. According to this model, the near-surface region of a photocathode, about 1 nm in thickness, consists of Gd2O3 with the energy gap width of about 5.3 eV. The distance from the Fermi level to the conduction band bottom equals about 2.7 eV in the Gd2O3 bulk. In the forbidden gap below the Fermi level, the bulk states and filled surface states associated with structural defects. A complicated dipole layer appears on the surface, and this gives the substantial reduction of the work function.

The results of experimental researches concerning the initial stages of the interaction between the Si(001) surface covered with a chromium or titanium monolayer and molecular oxygen at exposures to 10 7 L (Langmuir) are reported. On the basis of experimental data, the coefficient of molecular oxygen sticking is calculated. It is shown that not only silicon but also titanium oxides are formed on the Si(001) surface covered with a titanium monolayer. The researches are carried out, by using the Auger electron spectroscopy method.

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