ELECTRONIC AND STRUCTURAL PROPERTIES OF Si–Gd–O ELECTRON EMITTER

Rare earth metals, when deposited and oxidized on semiconductor surfaces, can be an alternative to unstable compounds of alkali metals while creating stable and effective emitters with a low work function. A procedure giving rise to the adsorption of Gd and O atoms on the Si(100) surface and the formation of a Si–Gd–O film with a work function of about 1 eV in the near-surface region is described. The films have been studied using the Auger electron and photoelectron spectroscopy, as well as X-ray diffraction, atomic force and Kelvin probe force microscopy techniques. Information about their electronic properties, structure, surface morphology, and surface distribution of potential was obtained. The main component of the film formed on the Si surface is a polycrystalline Gd2O3 phase, which plays the role of a matrix containing textured microcrystallites of one of the following phases: SiO2, GdO2, or GdSi2. The film surface consists of salient clusters 20nm to 80nm in diameter and up to 20nm in height, as well as craters up to 90nm in depth. The surface relief inhomogeneities correlate with the surface distribution of the local work function. This correlation can also be a result of the piezoelectric effect in the strained crystallites of the textured phase located in the bulk of the film. The obtained system was stable in time under vacuum conditions and heating up to 600∘C. The method proposed for the formation of surfaces with a low work function making use of rare earth metals can be applied to create effective and stable electron emitters.