Papers by Keyword: Phosphorous

Abstract: Silicon on insulator (SOI) wafer has allowed the integrated circuit (IC) industry to create superior, high-performance solutions. In addition, doping techniques are vital in the silicon sector due to the need to regulate the material electrical properties. The spin on dopant (SOD) approach is an alternative method that involves spinning a solution containing dopant onto SOI wafers. This research aims to determine the impact of thermal diffusion temperature and soaking time on sheet resistance of doped SOI wafer using SOD approach. Additionally, the homogeneity of doping was studied by utilizing mapping techniques. Three inches boron-doped SOI wafers were cut and cleaned according to Radio Corporation of America (RCA) standards. N-type dopants of Filmtronics SOD P509 were deposited on SOI wafer by using a spin coater, for 40 seconds at 4,000 revolutions per minute (rpm). The thermal diffusion temperature and soaking time were set between 700°C to 1000°C for 30 to 120 minutes. After thermal diffusion, hydrofluoric acids (HF) were diluted and used to etch samples. All materials were evaluated using a four-point probe, Hall Effect and Atomic Force Microscope (AFM). The results show that when the thermal diffusion soaking time increases, sheet resistance decreases until activated dopants are saturated. When sheet resistance decreases, dopant concentration rises. Temperature and soaking time increase carrier density and surface roughness, while decreasing Hall mobility. From mapping techniques, it shows low non-uniformity value which less than 10% suggests good thermal diffusion control.

Abstract: In this work, studies of the doping effects on the electronic and structural properties of graphene were performed. Calculations have been done within the periodic density functional theory (DFT) as implemented in PWscf code of the Quantum Espresso Package. Graphene layers have been modeled using the 4x4 periodic supercells. The doping is explored considering phosphorus (P), aluminum (Al) and silicon (Si) heteroatoms. One heteroatom per supercell was considered. Electronic structure results show that the pristine graphene has a linear dispersion at high symmetry K point and zero gap. Band structure of graphene doped with Al atoms exhibit a metal behavior since a valence band crosses the Fermi level. Graphene doped with P also presents a metal behavior but in this case a conduction band crosses the Fermi level. In addition, when the dopant is Si the band structure shows a semiconductor behavior with a 0.3 eV gap. In all cases, the zero gap energy characteristic of graphene was changed by dopant heteroatom. The Dirac lineal dispersion relation is preserved only in the pristine graphene.

Abstract: The Ni-P and Ni-Co-P coatings were electrodeposited at the deposition current density of j_dep = -20 mA cm^-2. Thermal treatment of these coatings was conducted in air at 400^oC for 1 h. Scanning electron microscopy (SEM) was used for surface morphology characterization of the coatings. Phase composition was investigated by X-ray diffraction (XRD) method. Atomic absorption spectrometry (AAS) was applied to specify chemical composition of obtained coatings. It was found that introduction of Co into amorphous Ni matrix caused the surface development of the obtained deposit. The Ni-P coating revealed an amorphous structure. The Ni-Co-P coating was formed of the amorphous matrix and the amorphous alloy ingredient. Thermal treatment of the coatings allowed to obtain new multi-phase materials with slightly developed surface.

Abstract: Phosphorous (P) incorporated silicon nanoparticles (Si NPs) were synthesized by using inductive coupled plasma (ICP) and a specially designed double tube reactor.Their microstructures were investigated by injecting various amounts of PH₃ gas during the synthesis. Injection of PH₃ gas during the synthesis resulted in a change from crystalline to amorphous phase, a reduction of particle size as well as process yield. These results were attributed to a lower plasma density when higher amount of PH₃ was injected.From EDS, SIMS and XPS analysis, it was revealed that P was successively incorporated in Si NPs.However, secondary phases such as P₄ (red P) and P₂O₅were formed as amorphous ones in nanoscale when a relatively large amount of PH₃ was injected.

Abstract: To investigate the potential bioavailability and mobility of phosphorus (P) in suspended solids, the Standards, Measurements and Testing (SMT) programmers was employed to characterize the distribution of P in suspended solids from different treatment stage of KunmingWWTP.Results showed that: the main form of total phosphorus (TP) in suspended solids was inorganic phosphorus (IP) ,which accounted for 47%~60%.Amongdifferent forms of inorganic phosphorus, Iron-phosphorus was the dominant forms accounted for 82 % of total phosphorus while calcium-phosphorus was only the minor par. Throughout the process, the trend of changes in content is close between total phosphorus and organ phosphorus. Bioavailable phosphorus in suspended solids ranged from 5.903 mg·g^-1to7.376mg·g^-1 and occupied 89.64%to94.16% of the total phosphorus pool.

Abstract: To improve the selectivity of light olefins, Phosphorous modified ZSM-5 zeolites catalysts with different phosphorous content were prepared by impregnation and were used in the conversion of methanol to olefins. The properties of acidity and microporous structure of the phosphorous modified ZSM-5 zeolites were investigated by XRD, N₂-adsorption and desorption, and NH₃-TPD. The highest propylene yield (50.82%) was observed over the H-ZSM-5 modified with the phosphorus content at 9% (weight percent). The selectivity of propylene depended strongly on the phosphorus content in the zeolites; The enhancement of propylene selectivity with increasing phosphorous content was attributed to reduction of strong acid sites on the H-ZSM-5. Modification of the ZSM-5 zeolites with phosphorous also changes the microporous structure.

Abstract: In this work, effects of Nb and Ti on the as-cast microstructure of Cr8Mo2VSi cold work die steel are investigated. It is found that the addition of Nb and Ti can effectively refine the dendrites of the steel to equiaxed grains. At the same time, the amount of Cr carbides has been reduced and the morphology of Cr carbides has been improved accompanied with the presence of multi-carbides containing a great amount of Nb, Ti and Mo. In addition, the phosphorous in the steel is moved from the grain boundaries into the multi-carbides.

Abstract: Silicon steels and ferrites dominate soft magnetic materials. However, Soft magnetic materials using powder metallurgical techniques are gaining wide spread use in motor, compressors and other rotating devices. High-density Fe-P soft magnetic materials have been developed using hot powder forging route. It was observed that phosphorous addition (ranging from 0.30P-0.80P) enhances the soft magnetic properties of iron for AC applications. This new soft magnetic material offers many manufacturing advantages. Because of its low eddy current loss, it has good high frequency magnetic properties comparable to other soft magnetic materials. Also, it has been observed that phosphorous addition improves the final density of the resulting product.

Abstract: Two oxygen-free copper grades with purity of 99.99 % were studied by means of free decay inverted torsion pendulum at the temperature range of 90 – 300 K and frequencies of 0.5 – 2 Hz. One copper grade was oxygen free electrolytically refined copper with oxygen content of 1.2 wt. ppm. The other one was oxygen-free phosphorous-alloyed grade with oxygen content less than 5 wt. ppm and phosphorous content of 30 – 70 wt. ppm. Electrochemical hydrogen charging induces a complex internal friction peak in the studied copper grades. The observed internal friction peak has a relaxation origin with apparent activation enthalpy and pre-exponential factor for the oxygen-free grade of 0.276 ± 0.002 eV and 10^{-11.59 ± 0.08} s, respectively. The internal friction peak can be fitted by three broadened Debye peaks (P1, P2 and P3) with activation enthalpies and pre-exponential factors of 0.248 ± 0.003 eV and 10^{-11.4 ± 0.4} s; 0.297 ± 0.004 eV and 10^{-11.8 ± 0.2} s; 0.36 ± 0.04 eV and 10^{-12.7 ± 1.4} s, respectively. Phosphorous doping markedly reduces the height of the observed peak. It was also shown that prior deformation by tension suppresses high-temperature components of the complex internal friction peak. Mechanism of relaxation is presumably caused by interaction of H – H pairs (low-temperature component, peak P1), interaction of hydrogen atoms with dislocations (P2) and interaction of hydrogen with impurities (high-temperature component, peak P3). Absorption of hydrogen in the studied copper grades during electrochemical hydrogen charging was confirmed by the thermal desorption method.

Abstract: SiAlFe ferroalloy is widely used as a strong de-oxidation compound to substitute pure aluminum in the production of iron and steel. However, its wide application is limited by the frequent occurrence of self-crumbling phenomena and accompanied emissions of a small amount of toxic and explosive gases. This paper determined the corresponding affecting factors by primary investigation of SiAlFe ferroalloy. Then the influence of contents of carbon and phosphorous on the self-crumbling was studied. The results showed that samples containing more phosphorous crumbled more seriously and the content of phosphorous was suggested to be less than 0.03 wt %. The change of content of carbon did not affect the crumbling obviously, ranging from 0.1~0.7 wt %.