Cu Concentration In Solution Research Articles

A Study of Cu Metal Deposition on Amorphous Si Films from Cu Solutions for Low‐Temperature Crystallization of Amorphous Si Films

Discrete copper metal particles were deposited on amorphous Si films by the spin‐coating of Cu solutions, and they were utilized as surface nucleation sites for solid‐phase crystallization of the amorphous Si films. About 99% of the as‐deposited Cu metal particles from the 1000 ppm Cu solution were evaporated, and the residual Cu particles migrated to form metal clusters after annealing at 530°C for 10 min. The clusters acted as surface nucleation sites which caused a fractal growth with the shape of tree branches. The crystallization temperature of the amorphous Si films with Cu metal particles on them was much lower than that of a‐Si films without Cu metal. When the Cu concentration in the solution was above 100 ppm, the crystallization was generally enhanced with the increase in the Cu concentration. However, the amorphous Si film spin‐coated with 10 ppm solution crystallized faster than the a‐Si film with 100 ppm, because the increased pH in the Cu solution enhanced the deposition of Cu metal particles. The amount of the as‐deposited Cu atoms with 100 ppm Cu solution had a minimum value of . The crystalline fraction by annealing at 530°C for 20 h was proportional to the amount of the as‐deposited Cu metal, instead of the Cu concentration in solution.

Copper-Enhanced Solid Phase Crystallization of Amorphous Silicon Films

AbstractLow-temperature crystallization of amorphous Si (a-Si) films was investigated by adsorbing copper ions on the surface of the films. The copper ions were adsorbed by spincoating of Cu solution. This new process lowered the crystallization temperature and reduced crystallization time of a-Si films. For 1000 ppm solution, the a-Si film was partly crystallized down to 500°C in 20 h and almost completely crystallized at 530°C in 20 h. The adsorbed Cu on the surface acted as a seed of crystalline and caused fractal growth. The fractal size was varied from 10 to 200 prm, depending on the Cu concentration in solution. But the grain size of the films was about 400 nm, which was similar to that of intrinsic films crystallized at 600°C.

Interaction between Ca 2+ and dissolved organic carbon: implications for metal mobilization

To investigate the role of dissolved Ca on the sorption and complexation behaviour of dissolved organic carbon (DOC), and the effect on dissolved Cu concentration, batch sorption studies and titration experiments have been performed. Both adsorption and desorption studies showed that the DOC concentration depends on the presence of Ca. With increasing Ca content, the DOC concentration decreased as a result of sorption and precipitation processes. The formation of aqueous Ca-DOC complexes could be described well with a 1:1 Ca:DOC ratio. Log K CaDOC values for the formation of Ca-DOC complexes ranged from 3.7 to 4 in the low pH range (3.5 to 6, interaction with carboxyl groups) and from 5.8 to 6 in the pH range from 7 to 9 (interaction with phenolic groups). The results indicate that a large part of the available DOC is in a Ca form at near neutral pH values. In batch sorption experiments, the addition of Ca 2+ significantly reduced the DOC as well as the Cu concentration in solution. This indicates that sorption of Ca-DOC complexes at near neutral pH is more important in regulating the Cu solution concentration compared to cation exchange processes.

The Effect of Annealing on the Cu Distribution and AI2Cu Precipitation in Ai(Cu) Thin Films

AbstractThe Cu distribution in AI(Cu) thin films has been examined in blanket and patterned samples as a function of annealing. The Cu concentration in the Al grains, measured at room temperature, closely follows the solubility at the anneal temperature when a high cooling rate is used (-100 or -200°C/min) from the annealing temperature. With fine lines, the room temperature Cu concentration follows the solubility at the anneal temperature only at low anneal temperatures, ≤350°C. With higher temperatureannealing, >400°C, the room temperature Cu concentration in the Al grains was substantially less than the solubility at the anneal temperature. These differences are attributed to the smaller grain size in fine lines, which reduces the distance to grain boundaries. With blanket films, the Θ-phase (Al2Cu) precipitate morphology depends on the Al grain size and annealing temperature. With small Al grains (100-300 nm), the Θ particles are small (100-200 nm) and round whereas with large Al grains (0.5-2μm), the precipitates are long and irregularly shaped. The morphology of the Θ precipitates is constrained by the Al grain size. With fine lines, having a bamboo structure, the Θ precipitates are “wedge” shaped along grain boundaries or span the width of the line. The electromigration lifetime was found to depend strongly on the heat treatment used, an increase of 3X in lifetime was obtained for samples rapidly cooled from a temperature above the solvus curve as compared with samples subjected to additional aging at low temperatures. This is believed to be dueto the different concentrations of Cu in solution and to the size and distribution of Θparticles in the patterned lines.

Effects of inorganic speciation on the interpretation of copper adsorption by soils

SUMMARYA previous study with a range of soils indicated that adsorption of copper could not be adequately described by the Freundlich equation. Adsorption curves for all but a highly calcareous soil could be divided into two straight lines with a marked increase in slope at low solution concentrations.A computer program (QELIOS) has now been used to calculate the effects of pH, CO, partial pressure and different inorganic anions on the chemical equilibria of the systems used in the adsorption experiments. At pH 6–8.5, hydrolysed species play a major role in Cu speciation whereas CO2−3 species become important only at pH > 8.0. The sensitivity of Cu hydrolysis to pH changes and to total Cu concentration in solution provides a possible explanation for the two surface Freundlich curves for soils of pH 6–7, and for the lack of such double surfaces for soils of pH > 7.

Copper species in aqueous sewage sludge extract

The Cu in the saturation extract of dried Davis sewage sludge was mainly in a complexed form. A Cu2+ specific ion electrode was used to determine the extent of complexation. The adsorption coefficient for the complexed Cu on Yolo silt loam was 4 while for Cu added as CUSO4 it was 90 L kg−1 at relevant Cu concentrations in solution. Paper electrophoresis was used to define the Cu complexes according to their mobility in an electric field. Six fractions of positive, negative and neutral charge were isolated. The portion of Cu in the sludge which was water soluble increased significantly upon drying. The large percentage of complexed Cu and its relatively low adsorption on soil suggested that sewage sludge may, under certain conditions, be a source of Cu contamination of plant systems and, in extreme cases, of ground water.

Micronutrient Cation Complexing in Soil Solution: II. Complexing of Zinc and Copper in Displaced Solution from Calcareous Soils

AbstractZinc deficiencies are generally more widespread on calcareous soils than are Cu deficiencies. The concentration and the degree of complexing of Zn and Cu were measured in the soil solution of 20 calcareous soils from Colorado. The Zn levels in solution were generally less than 2 ppb with rarely more than 75% of the Zn being complexed. Copper levels generally ranged from 5 to 16 ppb in the soil solution with 98 to 99% of the Cu present as organic complexes. Thus, complexing increased the total Cu concentration in solution by a factor of about 100, whereas it increased the total Zn in solution by a factor of 4 or less. Compared to acid soils studied previously, soluble Zn levels were much lower and complexing of Cu was somewhat higher in calcareous soils.