Effect of Electron Bombardment on the Composition and Structure of CaF2/Si(111) Films
Abstract
Using the methods of Auger electron spectroscopy, scanning electron microscopy, and measuring the angular dependences of the coefficient of inelastically reflected electrons, changes in the morphology, composition, and structure of CaF2 surface layers under electron bombardment with an energy of Ee = 1–8 keV are studied. The composition of the CaF2 surface changes noticeably at Ee = 2–3 keV and an electron dose of D ≥ 1018 cm–2. It is found that at a dose of less than 1018 cm–2, electrons are incident on separate sections of the CaF2 film. As D increases, the sizes of these sections increase, and starting from D = 8 × 1018 cm–2, the boundaries of neighboring sections overlap. The surface is completely covered with Ca atoms. After annealing at 900 K, a single-crystal Ca film is formed. At Ee = 3 keV, the thickness of the Ca film is ~25–30 Å.