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We report the cathodic electrodeposition of cerium oxide thin films from cerium-chloride aqueous solutions on p-type Si(001) substrates under illumination. Transmission electron microscopy coupled with electron diffraction analyses show that the deposits exhibited a nanocrystalline structure with a significant amorphous fraction when a hydrogen peroxide additive is used. X-ray photoelectron spectroscopy analyses were used to evaluate the surface stoichiometry, revealing a significant reduction of Ce(III) replacing Ce(IV) ionic sites for deposits prepared from solutions containing hydrogen peroxide as an additive. Adherent, uniform, and transparent CenormalO2 films with controllable stroichiometry can be deposited on Si, which is what renders these deposits versatile candidates for technological applications.

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The protein GlnB-Hs (GlnB of Herbaspirillum seropedicae) in diazotroph micro-organisms signalizes levels of nitrogen, carbon, and energy for a series of proteins involved in the regulation of expression and control of the activity of nitrogenase complex that converts atmospheric nitrogen in ammonia, resulting in biological nitrogen fixation. Its structure has already been determined by X-ray diffraction, revealing a trimer of (36 kDa) with lateral cavities having hydrophilic boundaries. The interactions of GlnB-Hs with the well-known Si(111) surface were investigated for different incubation times, protein concentrations in initial solution, deposition conditions, and substrate initial state. The protein solution was deposited on Si(111) and dried under controlled conditions. An atomic force microscope operating in dynamic mode shows images of circular, linear, and more complex donut-shaped protein arrangement, and also filament types of organization, which vary from a few nanometers to micrometers. Apparently, the filament formation was favored because of protein surface polarity when in contact with the silicon surface, following some specific orientation. The spin-coating technique was successfully used to obtain more uniform surface covering.

We report on the surface morphology, crystalline, and electronic properties of Fe thin films potentiostatically eletrodeposited on hydrogen-terminated Si(111) substrates. Spontaneous reaction between Fe deposits and hydrogen-terminated Si surfaces have been observed at room temperature with formation of polycrystalline silicides normalFe2Si and normalFe5normalSi3 , together with metallic Fe having a body-centered cubic structure. X-ray photoemission spectroscopy and X-ray diffraction measurements have been performed to investigate the thermal stability between Fe and Si under high-vacuum thermal treatments up to 300°C .

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