Reduction of Fluorine Diffusion and Improvement of Dark Current Using Carbon Implantation in CMOS Image Sensor

Recently, the demand of a high resolution complementary metal-oxide semiconductor (CMOS) image sensor is dramatically increasing. As the pixel size reduces to submicron, however, the quality of the sensor image decreases. In particular, the dark current can act as a large noise source resulting in reduction of the quality of the sensor image. Fluorine ion implantation was commonly used to improve the dark current by reducing the trap state density. However, the implanted fluorine diffused to the outside of the silicon surface and disappeared after annealing process. In this paper, we analyzed the effects of carbon implantation on the fluorine diffusion and the dark current characteristics of the CMOS image sensor. As the carbon was implanted with dose of 5.0 × 1014 and 1 × 1015 ions/cm2 in N+ area of FD region, the retained dose of fluorine was improved by more than 131% and 242%, respectively than no carbon implantation indicating that the higher concentration of the carbon implantation, the higher the retained dose of fluorine after annealing. As the retained fluorine concentration increased, the minority carriers of electrons or holes decreased by more Si-F bond formation, resulting in increasing the sheet resistance. When carbon was implanted with 1.0 × 1015 ions/cm2, the defective pixel, dark current, transient noise, and flicker were much improved by 25%, 9.4%, 1%, and 28%, respectively compared to no carbon implantation. Therefore, the diffusion of fluorine after annealing could be improved by the carbon implantation leading to improvement of the dark current characteristics.

Quartz-quartz type light guides with low losses and a thin polymer shell for the near-IR spectral range.

The issues of obtaining silica optical fibers with SiO2/SiO2-F composition (where SiO2 is a core, and SiO2-F is a light-reflecting cladding) with low optical losses for the near-IR spectral range are considered. This fiber type is widely used in various fields of science and technology, including laser medicine. The study results of the dependence of the numerical aperture and fluorine concentration in silica glass of the formed fiber preforms on the Freon (C3F8) consumption in the gas phase when using a waveguide-type microwave plasmotron at the H10 wavelength, are presented. It is showed that to increase the fluorimeters sensitivity in the near-IR spectral range as probe fibers for detecting luminescence, it is promising to use quartz-quartz fibers with the “Heraeus” glass core and the reflective SiO2-F cladding with an increased fluorine content in the glass (up to 7 wt. %). In this case, the numerical aperture of such fibers will reach values up to 0.32. For laser procedures in ophthalmology, surgery, phlebology and etc., optical fibers with a standard numerical aperture 0.20-0.24 can be used (with a fluorine concentration in the glass up to 3 wt. %).

Analysis of Fluoride Contamination in Sheep Serum and in Water in the North East of Tunisia Ore Deposits

The north east of Tunisia ore deposits (Hammam Zriba) contain a large amount of fluorides constituting a risk of environmental pollution as well as risks to human and animal health. The aim of our work was to assess the levels of fluorides in the water and blood of sheep in the east of Tunisia region. This analysis study included 78 water samples and 60 blood samples taken during 3 days in the year 2019, from a sheep herd at Hammam Zriba delegation. The determination of fluorine concentration in the samples was carried out by potentiometry with a selective electrode type ISE combined Fluoride perfectION™. High Fluoride concentrations were found at a mean of 1.62 ± 1.18, 1.45 ± 0.98, and 2.65 ± 1.61 mg/l, respectively, in running, deep, and stagnant waters. In addition, 83.3% of the animals reared within 400 m of the study area had elevated fluoride levels in the blood exceeding the usual values (fluoremia> 0.15 mg/l). The concentration of fluoride in the blood of the animals decreases with increasing distance from the mine.

Hydrogeochemistry of fluoride in shallow groundwater of the abandoned Yellow River delta, China

Fluorosis is the most widespread and serious endemic disease in the abandoned Yellow River flooding delta of East China. One of the important causes of fluorosis is drinking high-fluorine groundwater. In this study, 313 groundwater samples were collected in the central part of the flooding delta to address the chemistry of high-fluoride groundwater, and 33 core samples were collected from one borehole of 150 m depth to analyse the vertical distribution characteristics of total fluorine and water-soluble fluorine. The fluorine concentration in groundwater ranges from 0.2 to 6.7 mg/L, and 72.8% of the samples have fluorine above the China maximum permissible limit of 1.0 mg/L for drinking water. These 313 samples can be divided into nine hydrochemical subtypes, and over 77% of the samples belong to the bicarbonate types. High-fluorine groundwater (over 3.0 mg/L) is generally alkaline water with high HCO3− and low Ca2+. The concentration of water-soluble fluorine decreases gradually with the increase of formation depth, and that in vertical sediment is negatively correlated with Ca2+ and Cl−, but positively correlated with HCO3−. According to the calculation by PHREEQC package, MgF+ and CaF+ are the dominant species controlling the endemic fluorosis of the study area.

Diferenciação oxidativa em dispositivos temporários de ancoragem de Ti6Al4V e aço 316L – estudo piloto

The aim of this pilot study was to test the hypothesis that temporary anchoring devices (TADs) made of 316L steel are more resistant to corrosion even in fluorine environment than DATs manufactured in addition to titanium alloys, for this Potentiostat electrochemical measurements were performed. Materials and Methods: Four pieces of each material were tested in each test set, an application of Fusayama artificial saliva was used as an electrolytic solution in this study of in vitro corrosion, without fluorine in its composition and in a second moment with 1500ppM of fluorine in its composition. In the test, a cathodic polarization was performed by increasing this voltage for 5 minutes or until the corrosion pins were obtained. In artificial saliva containing up to 1500ppmF- this test was repeated with new samples of each material in artificial saliva solution without fluorine. Results: The results of the induction current scale were inserted into OriginPro8 software for making value graphs. As there was a small number of samples, in order not to violate the study’s reliability no statistical test was performed. Among all metal alloys currently used the Ti6Al4V alloy showed good resistance to corrosion in artificial saliva. However, the corrosion of these alloys occurs in contact with high fluorine concentration, unlike 316L steel alloy, which in addition to corrosion makes surface passivation.

Evaluation of Antibacterial and Cytotoxic Properties of a Fluorinated Diamond-Like Carbon Coating for the Development of Antibacterial Medical Implants

Peri-implant infection is a serious complication in surgical procedures involving implants. We conducted an in vitro study to determine whether the use of a fluorinated diamond-like carbon (F-DLC) coating on a titanium alloy surface can prevent peri-implant infection. After applying the F-DLC, we evaluated its antibacterial and cytotoxic properties. The coating groups, containing controlled fluorine concentrations of 5.44%, 17.43%, 24.09%, and 30%, were examined for the presence of Staphylococcus aureus and Escherichia coli according to ISO 22196 for the measurement of antibacterial activity on plastics and other nonporous surfaces. Biological toxicity was evaluated using Chinese hamster V79 cells according to ISO 10993-5 for the biological evaluation of medical devices. In the control group, populations of S. aureus and E. coli substantially increased from 2.4 × 104 to (1.45 ± 1.11) × 106 colony-forming units (CFUs) and from 2.54 × 104 to (4.04 ± 0.44) × 106 CFUs, respectively. However, no bacteria colonies were detected in any F-DLC group with a fluorine concentration of ≥ 17.43%. In the biological toxicity study, an F-DLC coating with a fluorine concentration of 30% showed a colony formation rate of 105.8 ± 24.1%, which did not differ significantly from the colony formation rate of 107.5 ± 31.1% in the nontoxic control group. An F-DLC coating on titanium alloy discs showed excellent in vitro antibacterial activity with no biological toxicity.

Quantitative fluorine and bromine detection under ambient conditions via molecular emission

Typical MW-LIBS spectra for different fluorine concentration as indicated. This yields a Florine LoD of 106 ± 6 μg g−1.