Photovoltaic silicon produced by thermal plasma: Influence of atomic hydrogen on oxygen elimination and passivation of the crystal defects

1998 ◽  
Vol 13 (10) ◽  
pp. 2709-2720 ◽  
Author(s):  
D. Morvan ◽  
I. Cazard-Juvernat ◽  
J. Amouroux
Keyword(s):  
Thermal Plasma ◽  
Atomic Hydrogen ◽  
Inductively Coupled Plasma ◽  
Thermal Conditions ◽  
Crystal Defects ◽  
Photovoltaic Properties ◽  
Inductively Coupled ◽  
Residual Hydrogen ◽  
Very High ◽  
Method Show

The photovoltaic properties of the polycrystalline silicon depend on the crystallinity and the purity of the material. The thermal plasma process gives us an alternative method of silicon preparation since it is possible to produce an ultrahigh purity with simultaneously a passivation of crystalline defects and active impurities. We demonstrate the efficiency of the plasma purification process and particularly the influence of the atomic hydrogen in an argon thermal plasma on the photovoltaic properties of silicon. The results of the diffusion lengths measured by the photoelectrochemical method show that locally it rises up to 200 μm. We correlate these photovoltaic measurements with the properties of the crystal (defects and purity) by means of measurements by Fourier transform infrared spectroscopy (FTIR) at low temperature (6 K), four probes resistivity technique, scanning electronic microscopy, inductively coupled plasma (ICP), and neutronic activation analyses. We show that the increase of the purity explains the high me asured diffusion lengths. Nevertheless, the thermal conditions of the crystallization of the silicon, due to the specificity of the plasma, lead to defects such as dislocations for which density is particularly high (>106 dis/cm2). The results show that chemical reactions between the atomic hydrogen of the plasma and the oxygen of the silicon occur. They decrease the oxygen content in silicon from 3 × 1017 at./cm3 down to 2 × 1016 at./cm3, while the residual hydrogen in silicon is close to 2 × 1015 at./cm3. This passivates the dangling bonds of ultrapure silicon with a high thermal stability up to 1000 K. The objective of this paper is to demonstrate that the hydrogen in the plasma modifies the electronic properties of the material to achieve a very good photocurrent even though the dislocation density of the silicon is very high.

scholarly journals Gold Partitioning in a Model Multiphase Mineral-Hydrothermal Fluid System: Distribution Coefficients, Speciation and Segregation

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 890 ◽  
Author(s):  
Sergey Lipko ◽  
Vladimir Tauson ◽  
Valeriy Bychinskii
Keyword(s):  
Inductively Coupled Plasma ◽  
Fluid Phase ◽  
Distribution Coefficients ◽  
Crystal Defects ◽  
Geothermal Systems ◽  
Fluid System ◽  
Experimental Conditions ◽  
Inductively Coupled ◽  
Ms Analysis ◽  
Icp Ms

The characteristics of Au partitioning in a multiphase, multicomponent hydrothermal system at 450 °C and 1 kbar pressure were obtained using experimental and computational physicochemical modelling and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis. Sphalerite and magnetite contained 0.1–0.16 ± 0.02 µg/g Au and coexisted with galena and bornite which contained up to 73 ± 5 and 42 ± 10 µg/g Au, respectively. Bornite and chalcopyrite were the most effective Au scavengers with cocrystallization coefficients Au/Fe and Au/Cu in mineral-fluid system n–n × 10−2. Sphalerite and magnetite were the weakest Au absorbers, although Fe impurity in sphalerite facilitated Au uptake. Using the phase composition correlation principle, Au solubility in minerals was estimated (µg/g Au): low-Fe sphalerite = 0.7, high-Fe sphalerite = 5, magnetite = 1, pyrite = 3, pyrite-Mn = 7, pyrite-Cu = 10, pyrrhotite = 21, chalcopyrite = 110, bornite = 140 and galena = 240. The sequence reflected increasing metallicity of chemical bonds. Gold segregation occurred at crystal defects, and on surfaces, and influenced Au distribution due to its segregation at crystal interblock boundaries enriched in Cu-containing submicron phases. The LA-ICP-MS analysis of bulk and surficial gold admixtures revealed elevated Au content in surficial crystal layers, especially for bornite and galena, indicating the presence of a superficial nonautonomous phase (NAP) and dualism in the distribution of gold. Thermodynamic calculations showed that changes in experimental conditions, primarily in sulfur regime, increased the content of the main gold species (AuCl2− and AuHS0) and decreased the content of FeCl20, the prevailing form of iron in the fluid phase. The elevation of S2 and H2S fugacity affected Au partitioning and cocrystallization coefficients. Using Au content in pyrite, chalcopyrite, magnetite and bornite from volcanic-sedimentary, skarn-hosted and magmatic-hydrothermal sulfide deposits, the ranges of metal ratios in fluids were estimated: Au/Fe = n × 10−4−n × 10−7 and Au/Cu = n × 10−4−n × 10−6. Pyrite and magnetite were crystallized from solutions enriched in Au compared to chalcopyrite and bornite. The presence of NAP, and associated dualism in distribution coefficients, strongly influenced Au partitioning, but this effect does not fully explain the high gold fractionation into mineral precipitates in low-temperature geothermal systems.

scholarly journals Treatment of fly ash from power plants using thermal plasma

2017 ◽  
Vol 8 ◽  
pp. 1043-1048 ◽  
Author(s):  
Sulaiman Al-Mayman ◽  
Ibrahim AlShunaifi ◽  
Abdullah Albeladi ◽  
Imed Ghiloufi ◽  
Saud Binjuwair
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Fly Ash ◽  
Thermal Plasma ◽  
Inductively Coupled Plasma ◽  
Power Plants ◽  
Plasma Reactor ◽  
Atomic Emission ◽  
Inductively Coupled ◽  
Scanning Electron

Fly ash from power plants is very toxic because it contains heavy metals. In this study fly ash was treated with a thermal plasma. Before their treatment, the fly ash was analyzed by many technics such as X-ray fluorescence, CHN elemental analysis, inductively coupled plasma atomic emission spectroscopy and scanning electron microscopy. With these technics, the composition, the chemical and physical proprieties of fly ash are determined. The results obtained by these analysis show that fly ash is mainly composed of carbon, and it contains also sulfur and metals such as V, Ca, Mg, Na, Fe, Ni, and Rh. The scanning electron microscopy analysis shows that fly ash particles are porous and have very irregular shapes with particle sizes of 20–50 μm. The treatment of fly ash was carried out in a plasma reactor and in two steps. In the first step, fly ash was treated in a pyrolysis/combustion plasma system to reduce the fraction of carbon. In the second step, the product obtained by the combustion of fly ash was vitrified in a plasma furnace. The leaching results show that the fly ash was detoxified by plasma vitrification and the produced slag is amorphous and glassy.

High growth rate diamond synthesis in a large area atmospheric pressure inductively coupled plasma

1990 ◽  
Vol 5 (11) ◽  
pp. 2326-2333 ◽  
Author(s):  
M. A. Cappelli ◽  
T. G. Owano ◽  
C. H. Kruger
Keyword(s):  
Growth Rates ◽  
Atmospheric Pressure ◽  
Atomic Hydrogen ◽  
Inductively Coupled Plasma ◽  
High Growth ◽  
High Growth Rate ◽  
Diamond Synthesis ◽  
Large Area ◽  
Inductively Coupled ◽  
Hydrogen Flux

A study of diamond synthesis in an atmospheric pressure inductively coupled argon-hydrogen-methane plasma is presented. The plasma generated has an active area of 20 cm2 and a free stream temperature of approximately 5000 K. Deposition experiments lasting 1 h in duration have been performed in both stagnation flow and flat plate parallel flow geometries. The diamond film deposited in both configurations are nonuniform yet fairly reproducible. The variation in the growth rates at various regions of the substrate is attributed to the variation in the surface atomic hydrogen flux. Growth rates are as high as 50 μm/h, in regions of the substrate where the atomic hydrogen flux is expected to be large. Little or no growth is observed in regions where the atomic hydrogen is expected to recombine within the thermal boundary layer before arriving at the surface. Individual particles are analyzed by micro-Raman spectroscopy. Large (50 μm) size well-faceted particles show little evidence of non-diamond carbon content and are found to be under a state of compression, displaying shifts in the principal phonon mode as great as 3 cm−1.

scholarly journals Parametric Study of Compound Semiconductor Etching Utilizing Inductively Coupled Plasma Source

1996 ◽  
Vol 421 ◽  
Author(s):  
C. Constantine ◽  
D. Johnson ◽  
C. Barratt ◽  
R. J. Shul ◽  
G. B. Mcclellan ◽  
...  
Keyword(s):  
Cyclotron Resonance ◽  
Inductively Coupled Plasma ◽  
Electron Cyclotron Resonance ◽  
Plasma Source ◽  
Large Area ◽  
Inductively Coupled ◽  
Semiconductor Etching ◽  
Deposition Processes ◽  
Gan Etching ◽  
Very High

AbstractInductively Coupled Plasma (ICP) sources are extremely promising for large-area, highion density etching or deposition processes. In this review we compare results for GaAs and GaN etching with both ICP and Electron Cyclotron Resonance (ECR) sources on the same singlewafer platform. The ICP is shown to be capable of very high rates with excellent anisotropy for fabrication of GaAs vias or deep mesas in GaAs or GaN waveguide structures.

scholarly journals Coprecipitation of Co2+, Ni2+ and Zn2+ with Mn(III/IV) Oxides Formed in Metal-Rich Mine Waters

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 226 ◽  
Author(s):  
Sánchez-España ◽  
Yusta
Keyword(s):  
Trace Metals ◽  
Trace Metal ◽  
Mine Water ◽  
Inductively Coupled Plasma ◽  
Manganese Oxides ◽  
Mine Waters ◽  
X Ray ◽  
Inductively Coupled ◽  
Mn Oxides ◽  
Very High

Manganese oxides are widespread in soils and natural waters, and their capacity to adsorb different trace metals such as Co, Ni, or Zn is well known. In this study, we aimed to compare the extent of trace metal coprecipitation in different Mn oxides formed during Mn(II) oxidation in highly concentrated, metal-rich mine waters. For this purpose, mine water samples collected from the deepest part of several acidic pit lakes in Spain (pH 2.7–4.2), with very high concentration of manganese (358–892 mg/L Mn) and trace metals (e.g., 795–10,394 µg/L Ni, 678–11,081 µg/L Co, 259–624 mg/L Zn), were neutralized to pH 8.0 in the laboratory and later used for Mn(II) oxidation experiments. These waters were subsequently allowed to oxidize at room temperature and pH = 8.5–9.0 over several weeks until Mn(II) was totally oxidized and a dense layer of manganese precipitates had been formed. These solids were characterized by different techniques for investigating the mineral phases formed and the amount of coprecipitated trace metals. All Mn oxides were fine-grained and poorly crystalline. Evidence from X-Ray Diffraction (XRD) and Scanning Electron Microscopy coupled to Energy Dispersive X-Ray Spectroscopy (SEM–EDX) suggests the formation of different manganese oxides with varying oxidation state ranging from Mn(III) (e.g., manganite) and Mn(III/IV) (e.g., birnessite, todorokite) to Mn(IV) (e.g., asbolane). Whole-precipitate analyses by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES), and/or Atomic Absorption Spectrometry (AAS), provided important concentrations of trace metals in birnessite (e.g., up to 1424 ppm Co, 814 ppm Ni, and 2713 ppm Zn), while Co and Ni concentrations at weight percent units were detected in asbolane by SEM-EDX. This trace metal retention capacity is lower than that observed in natural Mn oxides (e.g., birnessite) formed in the water column in a circum-neutral pit lake (pH 7.0–8.0), or in desautelsite obtained in previous neutralization experiments (pH 9.0–10.0). However, given the very high amount of Mn sorbent material formed in the solutions (2.8–4.6 g/L Mn oxide), the formation of these Mn(III/IV) oxides invariably led to the virtually total removal of Co, Ni, and Zn from the aqueous phase. We evaluate these data in the context of mine water pollution treatment and recovery of critical metals.

A Study of Internal Standardization in Inductively Coupled Plasma-Mass Spectrometry

1987 ◽  
Vol 41 (5) ◽  
pp. 801-806 ◽  
Author(s):  
Joseph J. Thompson ◽  
R. S. Houk
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Internal Standard ◽  
Operating Conditions ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Ionization Suppression ◽  
Plasma Mass Spectrometry ◽  
Internal Standardization ◽  
Very High

Internal standardization is employed to compensate for ionization suppression in inductively coupled plasma-mass spectrometry (ICP-MS). By examination of the response of over 50 elements to a sodium matrix under different operating conditions, it is apparent that an internal standard is most effective when it is close in mass and ionization energy to the analyte. The extent of suppression and the relative order of suppression of various analyte elements can differ for various matrix elements. Generally, precision was improved by the use of internal standardization; the extent of improvement differed for different analyte elements and operating conditions. A comparison between ICP-MS with ultrasonic and pneumatic nebulization is described. The ultrasonic nebulizer usually exhibits better sensitivity and detection limits for analyte elements, unless the extent of suppression induced by the concomitant matrix is very high.

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