Effect Of Oxygen Atoms Research Articles

Numerical and experimental investigation of effect of oxygen concentration on grown-in defects in a Czochralski silicon single crystal

Grown-in defect-free wafers are required in silicon semiconductor devices. A point defect concentration simulation was performed along with an experimental investigation, demonstrating a wide range of oxygen concentrations from 1.6 × 1017 to 9.1 × 1017 cm−3 in crystals. Thus, the effect of oxygen atoms in a Czochralski silicon single crystal with grown-in defect behavior was revealed. Consequently, the increasing vacancy concentration trapped by the oxygen atom (oxygen coefficient) was estimated as 4.61 × 10−5 per oxygen atom. Previously, for obtaining the oxygen coefficient, a regression equation assuming thermal equilibrium concentrations of vacancy (V) and interstitial Si (I) was applied to the experimental results. However, the interface shape, thermal stress, and hot-zone structure of the experimental level needed to be arranged; this affected the grown-in defect behavior. In this study, the oxygen coefficient and thermal equilibrium concentration of V and I were determined uniquely without arranging the situations experimental level.

Effect of oxygen atoms and cyano groups on mixed gas separation of PIM-1 membranes: MD simulations

The polymer of intrinsic microporosity PIM-1 shows a unique structure prevented intra-chain and inter-chain aggregation and produces high porosity and the possibility of functionalization, it is considered as a promising candidate for applications in the field of gas separation. In this work, PIM-1 membranes were constructed with 21-step method via molecular dynamics (MD) simulations, the structure information of PIM-1 membrane and their separation performances on CO2/N2 mixture was explored. The influence of functional groups on adsorption and permeation behavior of CO2/N2 mixture was explored, the transport mechanism and separation mechanism were also illustrated. The simulation results revealed that the permeation behavior of CO2/N2 mixture through PIM-1 membrane is a solubility-dominated separation mechanism, and the cyano group in PIM-1 chain and terminal hydroxyl groups play an important role in the gas adsorption and permeation process. Overall, this study provides valuable insights for the design and preparation of high-performance membrane materials.

Effects of oxygen atoms and oxygen molecules on the electronic properties of modified black phosphorus

Black phosphorus has good properties, but oxidation of the surface can damage these properties. Surface modification, as a common technique, can effectively help materials to resist oxidation. However, metal-doped does not improve the oxidation resistance in an oxygen-rich environment although this has been widely used. Here we studied the reaction between nitrogen-doped black phosphorus and atomic oxygen and O 2 using first-principles. We found that the energy band structure of modified black phosphorus changed obviously after absorbing atomic oxygen and O 2 , indicating that modified adsorption has a good effect on the regulation of band gap. In addition, when the modified black phosphorus exhibits the advantages of band gap adjustment, it is necessary to pay special attention to the problem of oxidation. Our study provides abundant data and effective guidance for black phosphorus in the field of antioxidants.

Effect of oxygen atoms on the vibrational kinetics of CO2 and CO revealed by the use of a large surface area material

The effect of oxygen atoms on the vibrational kinetics of CO2 and CO is studied in a DC glow discharge at reduced pressure by means of in situ FTIR spectroscopy. For this study we used two SiO2-based surface configurations: a smooth Pyrex discharge tube and a large specific surface material. The larger surface area enhances the O atom surface recombination into O2, the dominant O atom loss mechanism in our discharge conditions. The O atom density is thus reduced down to 5%–10% of the density measured with the smooth Pyrex tube, without changing significantly any other relevant plasma parameter (such as reduced electric field, gas temperature or dissociation fraction). The experimental results show a remarkable increase of the vibrational excitation of both CO2 and CO with the large surface material, i.e. low O atom density, demonstrating that atomic oxygen is a strong quencher of the vibrations of both species. In addition we show that, contrary to what could be expected, the use of large specific surfaces does not necessarily lead to lower vibrational excitation. In our experimental conditions, the possible enhanced de-excitation at the surface is compensated by the removal of oxygen atoms. Therefore these experimental results also demonstrate that large surfaces, catalytic or not, may have a significant impact on the plasma kinetics by affecting the recombination of gas phase species.

Effect of oxygen atoms on graphene: Adsorption and doping

Abstract Graphene is an excellent material, which can be used in aerospace field. However, it was reported that when graphene works in an oxygen-rich environment, its surface inevitably absorbs oxygen atoms. And oxygen atoms are doped when graphene has defects. In this study, we investigate the effect of adsorption and doping of oxygen atoms on the properties of graphene using first-principles calculations. We found that the adsorption of single oxygen atom can only change the position of Dirac point. However, the adsorption of multiple oxygen atoms may lead to band gaps. Meanwhile, when graphene has defects, oxygen atoms can repair its lattice. But oxygen atoms also localize some electrons, giving graphene a larger band gap than pure defective graphene. This study is helpful to evaluate the properties of graphene in an oxygen-rich environment. At the same time, it has certain significance for the application of graphene in band gap engineering.

Electronic properties of graphene nanoribbons with periodical nanoholes passivated by oxygen

By using the first-principles method and the density-functional theory, the electronic properties of graphene nanoribbons(GNRs) with periodic nanoholes passivated by oxygen are studied. It is shown that for the zigzag graphene nanoribbon (ZGNR) in nonmagnetic state(NM), the metallic properties not only still remain but also are obviously enhanced after the holes are punched. But for the antiferromagnetic-state (AFM) ZGNR, after punching holes, it would be changed from semiconductor to metal. While for the ferromagnetic-state (FM) ZGNR, it can be transformed from metal to semiconductor or semimetal after punching holes. Besides, for the punched armchair graphene nanoribbon (AGNR), its band gap will be significantly widened. The in-depth analysis shows that these results are due to the effects of oxygen atoms on electronic properties of GNRs, and also due to the different quantum confinement effects from the neck subprime nanoribbon (NSNR) and edge subprime nanoribbon (ESNR) with different width and edge shape(zigzag or armchair). These findings are important for developing nano electronic devices.

Stabilizing Zigzag Single-Walled Silicon Nanotubes and Tailoring the Electronic Structures by Oxygen Atoms: First-Principles Studies

The effects of oxygen atoms in stabilizing zigzag single-walled silicon nanotubes (SWSiNTs) have been studied by using first-principles calculations within density functional theory. The incorporation of oxygen atoms in the form of silicon monoxides into the (8,0)SWSiNT are found to not only stabilize the SWSiNT but also tailor the electronic structures from semiconducting to metallic. These findings will promote the fabrication and the utilization of silicon suboxide nanotubes which may find potential applications in nanoscale electronics and optoelectronics.

Guided ion beam studies of the reactions of Vn+ (n=2–17) with O2: Bond energies and dissociation pathways

The kinetic energy dependence of the reactions of Vn+ (n=2–17) with oxygen is studied using a guided ion beam mass spectrometer. In all but the smallest clusters, the primary reaction process at low energies is the formation of a vanadium cluster dioxide ion which then loses one or two vanadium atoms or a vanadium oxide diatom (VO). Vanadium atom loss is the preferred reaction pathway for large clusters (n⩾5), whereas loss of VO is more favorable for the smallest reactant clusters (n⩽4). As the collision energy is increased, these primary products dissociate further by loss of additional vanadium atoms. Bond dissociation energies of the vanadium cluster oxides are determined by analysis of the kinetic energy dependence of several different products. The effect of oxygen atoms on the stabilities of vanadium cluster ions is discussed and compared with bulk phase thermochemistry.

シリコン基板内応力特異場における転位発生強度の酸素濃度依存性

With the increasing level of integration in semiconductor devices, new types of silicon wafers are developed to respond to the needs arising in electric design. The new types of wafers contain different concentrations of oxygen atoms then the former silicon wafers. Therefore, the oxygen concentration dependence of dislocation generation in silicon substrates is investigated. The specimens were silicon substrates with (on the surface) stressed thin-film bands, at whose edges stress singularity fields were formed. The Dislocation-generation strength was measured by changing the bandwidth and detecting limit bandwidth for dislocation generation. Since the limit bandwidth did not depend on the oxygen concentration, it was shown that the oxygen atoms do not affect the generation of dislocations. On the other hand, the dislocation density depended strongly on the oxygen concentration. Since the density is related to the mobility of dislocations, it can be said that the effect of oxygen atoms is only the mobility of dislocation.

Effect of Oxygen Atoms in the Solvent and Ligand in Graphite-Furnace Atomic Absorption Spectrometry of Organotin and Inorganic Tin with the Use of an Organopalladium Matrix Modifier

Effect of Oxygen Atoms in the Solvent and Ligand in Graphite-Furnace Atomic Absorption Spectrometry of Organotin and Inorganic Tin with the Use of an Organopalladium Matrix Modifier

Thermotropic properties and conformational studies on poly(triethylene glycol p,p'-bibenzoate) and poly(octamethylene p,p'-bibenzoate)

It was found that the effect of oxygen atoms in the spacer on the thermotropic ability of poly(p,p'-bibenzoate)s is to lower the transition temperatures and to diminish theability to develop a three-dimensional crystal. Moreover, a smectic S c mesophase is formed in the case of poly(triethyleneglycol p,p'-bibenzoate). The integrated distributions of the angles between two successive rigid coresand the distribution of chain sequence extensions are calculated by the RIS model and were found to be very sensitive to the presence of oxygen atoms in the spacer.

Diacetone glucose architecture as a chirality template I. Crucial effects of the intramolecular oxygens upon the LiAlH 4 reduction of the propargyl alcohol of 3- C-ethynyl-1,2:5,6-di- O-isopropylidene-α- D-allofuranose derivatives

The facile as well as regio- and stereoselective reactivity of 3-C-ethynyl-1,2:5,6-di-O-isopropylidene-α-D-allofuranose derivatives for LiAlH 4 reduction into the corresponding ethenyl derivatives were investigated. The effect of oxygen atoms on the reduction is discussed by means of semi-empirical MO calculation.

Flexible carbonaceous and graphitized films by pyrolytic chemical-vapor-deposition method from hydrocarbons containing oxygen atoms

Carbonaceous films with high conductivity have been prepared by a pyrolytic chemical-vapor-deposition method using hydrocarbons containing oxygen atoms, phenols, carboxylic acids, etc. The films obtained are self-supporting and flexible. The electrical conductivities of the films depend on the pyrolyzing temperature but not remarkably on the kind of raw materials. The films are converted to high-quality graphitized films with conductivity of 1.6×104 S/cm by heating under an Ar atmosphere to 2800 °C. The electrical conductivity and thermoelectric power of the films are examined as a function of the heat-treatment temperatures. The excellent property of the films obtained in this study seems to arise from the effect of oxygen atoms in the process of condensed aromatic ring formation by pyrolysis.

A MODEL STUDY OF REGENERATION PROCESS IN RHODOPSIN VISUAL CYCLE

Abstract The regeneration process in rhodopsin was studied by an estimation of isomer population at photoequilibrium for the model compounds of N-retinylidene phosphatidylethanolimine. We suggested that the preferential formation of 11-cis isomer may be induced by the through-bond effect of oxygen atom of imine moiety of a Schiff base.

High Resistivity Transparent ZnO Thin Films

Zinc oxide (ZnO) is a material which, under ordinary circumstances, has a small oxygen deficiency. This lack of chemical makes ZnO an n-type semiconductor with a typical resistivity of 1–100 Ωcm. In this work crystalline ZnO films with resistivities from 108-1013 Ωcm have been obtained by reactively dc sputtering metallic zinc or rf sputtering ZnO in an argon-oxygen mixture or in pure oxygen. Films were deposited on metallic substrates such as gold or zinc or insulating substrates such as quartz or sapphire maintained at temperatures from −100 °–+200 °C. The high resistivity is thought to result from a decrease in the normal oxygen deficiency of ZnO. Three mechanisms are likely to be involved hi the enhanced oxygen incorporation: (1) oxygen atoms in the discharge, (2) dissociation of oxygen ions on impact with the surface, and (3) implantation of oxygen ions in the film. Although quantitative data are not available at this time it is clear that the effect of oxygen atoms is large since they are formed bot...

Absolute configuration determination using the anomalous scattering of Cu-K ? X-rays by oxygen atoms: cellobiose

The anomalous scattering effects of oxygen atoms have been measured and their usefulness confirmed by the determination of the absolute configuration of cellobiose.

Effect of Oxygen Atoms on the Vibrational Relaxation of Nitrogen

The vibrational relaxation of nitrogen in the presence of oxygen atoms generated by the decomposition of ozone has been studied behind incident shock waves in the temperature range 3000°–4500°K. Relaxation of the nitrogen was followed by measurement of the postshock density gradient using a laser-beam deflection technique. Analysis of the data to yield PτN2–O, the relaxation time for nitrogen dilute in 1 atm of oxygen atoms, requires consideration of the simultaneous effect of molecular oxygen produced by the ozone decomposition The values obtained for PτN2–O are subject to some uncertainty, but clearly lie below those for pure nitrogen by nearly two orders of magnitude. The results are interpreted as evidence of a chemical effect.

The effect of oxygen atoms on the vibrational relaxation of oxygen

The vibrational relaxation of oxygen in the presence of oxygen atoms generated by the thermal decomposition of ozone has been studied in shock waves over the temperature range 1600°–3300°K. Relaxation of the oxygen was followed densitometrically with the laser schlieren technique. The presence of small quantities of oxygen atoms has a pronounced effect on oxygen relaxation. Detailed analysis of the data results in the simple expression PτO2−O=(4.35±0.19)×10−8−(7.75±0.81)×10−12 T atm·sec for the relaxation time of oxygen dilute in an atmosphere of oxygen atom. It is concluded that this system provides an unambiguous example of a strong chemical effect.