Microstructural and Optical Properties Modifications Induced by Plasma and Annealing Treatments of Lanthanum Oxide Sol−Gel Thin Films

Abstract

Lanthanum oxide (La2O3) thin films have been prepared on Si(100) substrates through a sol−gel process from the lanthanum methoxyethoxide (La(OCH2CH2OCH3)3) precursor. To study the effects of different postdeposition treatments on film microstructure and optical properties, the as-deposited layers have been annealed at different temperatures between 200 and 700 °C in air or forming gas (H2 10% in N2) for 1 h. Low-temperature (300 °C) remote O2 plasma processing has also been applied to both as-deposited and previously annealed samples. Films have been fully characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (SE), glancing incidence X-ray diffraction (GIXRD), and atomic force microscopy (AFM). In particular, microstructure and optical properties correlations were accomplished by exploiting spectroscopic ellipsometric investigation. It has been found that thermal annealing at temperatures around 500 °C leads to subcutaneous oxidation of...