Papers by Keyword: Silicon Oxide (SiO)

Abstract: Silicon oxide (SiOx) were deposited on many substrates such as silicon, glass, and poly (ethylene terephthalate) (PET) and widely used in industry due to their excellent impressive barrier, electrical, optical and eco-friendly properties. However, few publications that focus on paper as substrate in sputtering have been found. SiOx films were deposited on papers by radio frequency (RF) magnetron sputtering. The influences of process parameters, RF power density and deposition time on deposition rate, surface roughness, mechanical properties and humidity barrier of the films were investigated. The result from atomic force microscopy (AFM) applied to investigate the surface morphologies showed that papers being deposited SiOx (SiOx/Paper) films with the average roughness were much more homogenous and smoother than raw papers. Horizontal, vertical elastic modulus and yield strength of SiOx/Pap clearly increased. The water vapor transmission rate of SiOx/Paper films, which prepared at RF density of 2.78 W/cm2, argon (Ar) flux of 40 sccm and deposition time of 36 min decreased 15times, and the oxygen transmission rate did 10 times. Additional investigations regarding printability focusing on the color reproduction properties were also carried out.

Abstract: Dry and wet oxidation silica films doped with silicon ions were prepared using metal vapor vacuum arc (MEVVA) ion source implanter. The does of Si ion beams were kept constant at 3×1016 /cm2 and the energy varied from 42KeV to 70KeV. Five photoluminescence (PL) bands at the wavelength of 560nm, 580nm, 620nm, 650nm and 730nm have been observed at room temperature in all samples. The results of XRD showed none of Si nanocrystals were formed in the as-implanted silica films and originations of the PL bands were defects introduced by implantation. The 560nm PL band originated from oxygen surplus defect small peroxy radical (SPR), whereas the PL bands which ranges from the wavelength of 620nm to 730nm were attributed to non bridge oxygen hole center (NBOHC). Elevating implantation energy resulted in intensity increasing of 560nm PL band of dry oxidation samples but had inverse effects on wet oxidation samples. Influence mechanism of implantation energy on the defect photoluminescence was discussed in this article.

Abstract: In the present paper we discuss the defects at the oxide/Si interface and the structure of silicon oxide films grown on plasma hydrogenated (100) and (111)Si. The effect of oxide thickness ranging from 7 to 40 nm on the interface parameters was examined. Electrically active defects were characterized through C-V and G-V measurements. The dependence of the refractive index on oxide thickness was studied. Information on the oxide structure was inferred through the refractive index evaluated from ellipsometric measurements. From both, the electrical and optical results a characteristic oxide thickness was found, below which the oxide structure is different from SiO2, most probably SiOх. It is related to a modified Si surface during the pre-oxidation plasma treatment and its value depends on Si orientation and pre-clean conditions. A characteristic oxide thickness of 13 nm was found for Si hydrogenated without heating and, of 9 nm for Si hydrogenated at 300oC.

Abstract: Studies of oblique deposited nanostructured SiOx films by ellipsometric and IR spectroscopies are presented, as additional information is obtained by scanning electron microscopy (SEM). The films were deposited onto Si substrates under a 75° incidence vapor by vacuum evaporation of SiO and were annealed in Ar at 950oC. The thickness and composition of the films were estimated from the ellipsometric data analysis applying the Bruggeman effective approximation theory. Three-layer optical model described satisfactory the annealed film structure and verified the formation of nanocrystalline Si clusters. SEM micrographs showed that evaporated films consisted of silicon oxide pillars separated by air space and tilted at an angle of ~57o to Si substrate surface. The thin silica pillars were most probably free from Si-SiO2 interface leading to absence of strong absorption on LO vibrations in the IR spectrum. The estimated porosity factor was ~62 %. By annealing, the film oxidized to SiO2 but it remained columnar with a porosity factor of ~47 %.

Abstract: In this paper the new method for determination of luminescent centers concentration are discussed. While the possibility of electron traps determination and definition of its activation energy are suggested. The cathodoluminescent (CL) method was used. The determination of luminescent centers concentration in silicon oxide is based on the measurements of dependences of CL intensity on electron beam current. The presence and energy of activation of electron traps were studied by measurement of rise time and decay of luminescent band during the stationary irradiation of silica by electron beam.

Abstract: Accumulation of hydrogen in Czochralski silicon implanted with N2+ (Si:N; N dose, DN=1–1.8x1018 cm-2; energy E=140 keV) or O2+ (Si:O; DO=1x1017 cm-2; E=200 keV), processed at up to 1400 K (HT) under enhanced Ar pressure, up to 1.2 GPa (HP), and followed by treatment in hydrogen (deuterium) plasma, was investigated by Secondary Ion Mass Spectroscopy. Implantation produces buried amorphous layer. As determined by transmission electron microscopy, subsequent HT-HP processing results in a formation of a specific sample microstructure. In plasma treated as-implanted Si:N, hydrogen accumulates at a depth of about 50 nm, up to concentration 2x1021 cm-3. This concentration is twice lower at a depth ≈ 80–250 nm. Deuterium content remains almost unchanged after plasma treatment of Si:N prepared by processing at 1270 K while it is strongly dependent on DN and on HP. In plasma treated Si:O, prepared by processing at 920-1230 K, hydrogen profile corresponds to that of implanted oxygen and decreases with HP. Comparative analysis of hydrogen accumulation and its subsequent release at 720-920 K in the Si:N and Si:O structures indicates that the capacity of buried layers in Si:O to getter and to preserve hydrogen is higher than that in Si:N.

Abstract: Slow positron beam technique has been applied to measure the Doppler broadening spectra for single crystals of Cu, SiO2, graphite, virgin Si, and Si without oxide film. The results show that the Cu ratio curve shows a high peak due to Cu having 10 electrons in the 3d shells. The ratio curve of SiO2 is higher than that of graphite. For the single crystal of Cu, SiO2, graphite, and Si without oxide film, the S (W) parameters decrease (increase) as positron implantation energy increasing. Defects on the surface lead to higher S (lower W) value. For the virgin Si and the thermally grown SiO2-Si samples, the S (W) parameters increase (decrease) as positron implantation energy increasing. It can be due to Si atom at surface, with two dangling bonds, tend to form silicon oxide with O. The W parameter for the single crystal of Cu is relatively high as compared with that of the single crystals of SiO2 and graphite.

Abstract: An investigation is reported by coating BaMgAl10O17:Eu2+ phosphor by silicon oxide using catalyzed atomic layer deposition. Nanoscaled SiO2 films were prepared at room temperature using tetraethoxysilane (TEOS), H2O and NH3 as precursors, reactant gas and catalyst, respectively. AES analysis showed the surface composition of coated phosphor was silicon oxide. In TEM and FE-SEM analysis, the growth rate was about 0.7 Å/cycle and the surface morphology became smoother and clearer than that of uncoated phosphor. The photoluminescence intensity (PL) increased up to 11.04% as ALD cycle increased up to 200 ALD cycle. This means that the reactive surface of uncoated phosphors is uniformly grown with stable silicon oxide to reduce the dead surface layer without change of bulk properties. Moreover, it is found that nanoscaled SiO2 films are quite effective for the improvement of the aging characteristics of photoluminescence.

Abstract: To retain the optimum hydration level of the proton exchange membrane fuel cell (PEMFC) without humidification sub-system, a novel self-humidifying composite membrane was fabricated by the technology of Si[OCH2CH3]4 in situ sol-gel reaction in a commercial Nafion 112 membrane. The physico-chemical properties of the membrane were studied by means of AFM, SEM and AC impedance. These results showed that the nano-SiO2 reactant was uniformly distributed in the composite membrane. It was found that the proton conductivity increased observably by dispersing 3 wt % nano-SiO2 in the composite membrane at low water content, and the SiO2/Nafion composite membrane improved the self-humidifying performance of PEMFC.

Abstract: We have demonstrated the growth of SiOx nanowires by the simple heating of the Au-coated Si substrates. We used X-ray diffraction, scanning electron microscopy, energy dispersive x-ray spectroscopy, and transmission electron microscopy to characterize the samples. The as-synthesized SiOx nanowires had amorphous structures with diameters in the range of 10-70 nm. We have discussed the possible growth mechanism.