Thickness dependence of the growth of magnetron-sputtered TiO2 films studied by Raman and optical transmittance spectroscopy

Abstract

Thin sputtered films of TiO2 of various thicknesses are characterized by their strain along the crystalline c−axis. The Raman B1g 519 cm−1 mode experiences a strong blue shift, whereas the Eg 144 cm−1 peak is at the standard position for all samples. The Raman intensity of the prominent Eg 144 cm−1 peak increases upon annealing at 300 °C, contrary to the integral intensity of XRD reflexes which remains constant. The half−width of the Eg 144 cm−1 peak is determined by the crystallite size. Dielectric modelling of the optical transmittance spectra indicates, for all samples, the existence of defect states leading to transitions 0.3−0.5 eV lower than the band gap. The growth process becomes stationary for a film thickness above 100 nm for rf−sputtered and above 200 nm for dc−sputtered films.

Tailoring the protonic conductivity of porous yttria-stabilized zirconia thin films by surface modification

“…379 [B 1g ] and 516 cm -1 [A 1g ], confirming the successful deposition of anatase TiO 2 (cTiO 2 ) with tetragonal symmetry. [46][47][48] From the literature, it is known that, below a critical thickness of approximately 6 nm, ALD-derived titania layers are amorphous in nature, 49 in agreement with the Raman results.…”

Impact of Vanadium Loading and Thermal Aging on the Surface Properties of Titania-Supported Vanadium Oxide

“…This relative change holds also for the other samples investigated, and in fact, it intensifies slightly with increasing vanadium loading. Based on the knowledge that the modes at 396 and 516 cm –1 are associated with vibrations of bonds aligned with the c -axis, whereas the mode at 639 cm –1 is associated with vibrations of bonds on the a-b plane, and with reference to previous works focused on the effect of size and orientation of TiO 2 films on Raman intensities, , the observed relative intensity change is here proposed to be due to an intrinsic morphological transition. In other words, the lower relative intensity of the modes at 396 and 516 cm –1 observed after aging may come from a new morphology with a smaller fraction of bonds along the c -axis (cf.…”

Studying the structural and optical properties of Er3+ doped TiO2 powders synthesized by the sol-gel process

“…No peaks associated with the defect states of TiO 2 appeared in the visible PL emission, implying that the energy can transfer from the defects in TiO 2 to the 4 F 7/2 level of the Er-ions. Subsequently, the electrons relax from 4 By contrast, under direct excitation at 980 nm, known as an up-conversion process, the emission of green and red colours may occur due to multiple photons. The PL spectrum was obtained at different excitation powers P ranging from 0.09 W to 0.6 W, as shown in figure 6(a), to determine the number of photons n contributing to the up-conversion process.…”

“…Further, TiO 2 is a multi-phase material, which depends on fabrication parameters, calcination temperature, and pressure. Many researchers have shown that TiO 2 can be converted from anatase to rutile phase by raising the calcination temperature [4,5]. Moreover, TiO 2 nanomaterials also have various morphologies, such as spherical, tubular, rod, wire, plate, and filament shapes, which are suitable for manufacturing optoelectronic devices [6,7].…”