Rares Scurtu

Spectroellipsometric Characterization of Multilayer Sol-Gel Fe2O3 Films

Multilayer Fe2O3 films were deposited by the sol-gel method on glass substrates using three successive deposition procedures. The films were thermally treated for 1 h at 300°C.The optical and microstructural properties of these films were investigated by spectroscopic ellipsometry (SE) in the 500–1000 nm range. The optical gap was found by fitting the dispersion of the film refractive index (n) with the Wemple-DiDomenico (WDD) formula.The ellipsometric measurements showed also that the Fe2O3 films are anisotropic. The birefringence values (Δn) of the sol-gel films (0.05–0.08) are smaller than the large values of the Fe2O3 (which are around 0.28) but increase with the crystalization of the films. AFM mesurements showed that the films treated at 300°C start to crystallize.

Fermi Level Pinning at n-GaAs(110) Electrodes

Abstract Mott-Schottky plots and potential-dependent second harmonic generation measurements performed at n-GaAs(110) electrodes in 1 N H2SO4 revealed the Fermi level pinnig near midgap. The possible nature of the bandgap states is discussed on the basis of the information provided by electrochemical impedance spectroscopy and in situ spectroscopic ellipsometry studies

SiO2-ZrO2 Sol-Gel Nanostructured Thin Films with Optical Properties

SiO2-ZrO2 based nanometric multilayers films have been prepared by sol-gel method from metallorganic precursors by low temperature polymerization reactions. Simultaneous gelation of both cations was realized. Homogeneous and transparent films were poduced on glass substrate at room temperature by dipping procedure. Each deposited layer was thermal treated 1h at 300°C. The coatings were characterized by XRD, spectroellipsometry (SE), UV-VIS spectroscopy and AFM method. The influence of number of coatings and thermal treatments on the optical and structural proprieties of the films was established.