Boron Doping Concentration Research Articles

Effect of boron doping levels on the piezoresistive properties of boron-doped diamond films prepared by HFCVD

The exceptional piezoresistive properties of boron-doped diamond (BDD) films render them highly promising for pressure sensor applications. These properties are closely associated with the doping concentration, crystal structure, and substrate material. In this study, BDD films with varying boron concentrations (B/C=500-8000 ppm) were fabricated on silicon and diamond substrates using hot-filament chemical vapor deposition (HFCVD) equipment. The relationship between surface grain characteristics, grain boundaries, and gauge factor (GF) of BDD films deposited on different substrates was systematically examined. The concentration of boron doping significantly influenced the surface morphology, electrical resistivity, and GF of the BDD films. The grain size of BDD films initially increased as the boron doping concentration was raised from 500 ppm to 2000 ppm; however, it subsequently decreased when the boron doping content exceeded 2000 ppm. Moreover, we found that the piezoresistive impact of a BDD film is strongly correlated to its grain size; larger grain sizes result in higher GF values. Notably, compared to those on silicon substrates, the BDD films deposited on diamond substrates exhibited superior piezoresistive characteristics. Specifically at a doping concentration of 2000 ppm, a GF as high as 284 was achieved for the BDD film on a diamond substrate compared to only 140 for that on a silicon substrate.

The Role of Oxygen on Defects Formation during Advanced Silicon Process Technologies

Impact of oxygen in silicon substrates and the formation of oxide precipitates have been widely studied in the past because of the detrimental electrical recombination and its effect on yield [1,2]. The origin of interstitial oxygen (Oi) is not only limited to the substrate but also comes from the nature of the oxide that may be deposited on it [3]. Interstitial oxygen plays a direct role in the formation of bulk microdefects (BMDs) resulting from oxygen precipitation during low-temperature Front-End anneals at 650-800°C [4,5]. The latter are of interest for the mechanical robustness of substrates, contributing to the pinning of slip lines (SL) and for the reliability of devices thanks to an internal gettering effect, but can also be harmful by emitting dislocations when they are too numerous (> 1 x 1010 BMD.cm-3) [5, 8].In this paper, we have reviewed the different impacts of interstitial oxygen on silicon substrates during thermal annealing through 3 phenomena: (i) the influence of Oi on the reduction of the slip lines by the pinning effect, (ii) the formation of BMDs induced by Oi and their interactions with dopants during implantation processes, (iii) the BMDs limited formation in the specific case of high resistivity (HR) silicon substrates. We focused on standard and high resistivity silicon substrates obtained by Czochralski (CZ) method, used in advanced technologies for various applications (digital, bipolar, power, photonic, etc.).To highlight the impact of interstitial oxygen, firstly on the mechanical properties of substrates, we studied the same p-type silicon substrates with two ranges of Oi concentration (5.33 x 1017 and 7.23 x 1017 at.cm-3), both annealed by furnace oxidation below 1000°C and N2 annealing above 1000°C. Figure 1 clearly shows the effect of a minor difference in Oi concentration on the number of slip lines detected by Pattern Wafer Geometry (PWG) measurements (Figure 2). Despite extrinsic process parameters to consider in the occurrence of slip lines, these results demonstrate the enhancement of slip line pinning by interstitial oxygen.Bulk microdefects in silicon are known to interact with dopants [6]. To investigate this point, we compared the BMD occurrence in non-implanted and antimony-implanted (2 x 1015 at.cm-2) silicon substrates using micro-photoluminescence imaging. These substrates contain relatively high Oi concentrations (up to 6.7 x 1017 at.cm-3) and have been subjected to oxidation and rapid thermal annealing (RTA) above 900°C. After adjusting for background contrast in the implanted and non-implanted regions, Figure 3 shows different trends in BMD density evolution as a function of the probed depth. We assume that a mechanism based on a mechanical stress field induced by the position of the Sb-implanted atoms in the lattice limits the nucleation of oxide precipitates [7]. However, further characterization methods are required to confirm the influence of dopants on the BMD density.Finally, high resistivity silicon substrates are being considered to significantly improve devices performance, particularly in high frequency and photonics applications [8, 9]. However, the understanding of BMD formation is poorly documented in the literature. These CZ-Si substrates are characterized by low oxygen content (< 3 x 1017 at.cm-3) and low boron dopant concentration (< 1 x 1014 at.cm-3). At such low values, the expected oxygen precipitation is very different from that of standard p-type silicon [8, 10]. We investigated the effect of these parameters on BMD formation through precipitation thermal treatments (N2 + O2 anneal > 1000°C). Figure 4 illustrates the important difference in BMD formation depending on the substrate characteristics (standard resistivity high-Oi versus high resistivity low-Oi silicon) after the same thermal treatment. BMD defects were generated in large quantities in standard silicon (3 x 109 BMD.cm-3), whereas no BMDs were observed in HR silicon.In summary, we have demonstrated the impact of interstitial oxygen (coming from substrates and processes) on defect generation, particularly BMD, in silicon technology. In controlled proportions, they play an important role in the proper functioning of devices and very often result from the fine tuning between substrate characteristics and process conditions.[1] Jun Fujise et al 2018 JJAP. 57 035501[2] Zijing Wang et al 2022 APE 15 071004[3] G. Kissinger et al 2019 ECS J3ST. 8 N79[4] Maria Porrini et al 2018 ECS Trans. 86 7[5] Hirofumi Shimizu et al 1985 JJAP. 24 815[6] Hideki Tsuya et al 1983 JJAP. 22 L1[7] Oleksandr Oberemok et al 2014 PSS. 11 163439[8] Isabelle Bertrand et al 2022 ECS Trans. 31 108[9] Jarosław Judek et al 2017 JEM. 46 5589-5592[10] Kaoru Kajiwara et al 2019 PSS. 17 216 Figure 1

Single-crystal vs polycrystalline boron-doped diamond anodes: Comparing degradation efficiencies of carbamazepine in electrochemical water treatment

The ongoing challenge of water pollution by contaminants of emerging concern calls for more effective wastewater treatment to prevent harmful side effects to the environment and human health. To this end, this study explored for the first time the implementation of single-crystal boron-doped diamond (BDD) anodes in electrochemical wastewater treatment, which stand out from the conventional polycrystalline BDD morphologies widely reported in the literature. The single-crystal BDD presented a pure diamond (sp3) content, whereas the three other investigated polycrystalline BDD electrodes displayed various properties in terms of boron doping, sp3/sp2 content, microstructure, and roughness. The effects of other process conditions, such as applied current density and anolyte concentration, were simultaneously investigated using carbamazepine (CBZ) as a representative target pollutant. The Taguchi method was applied to elucidate the optimal operating conditions that maximised either (i) the CBZ degradation rate constant (enhanced through hydroxyl radicals (•OH)) or (ii) the proportion of sulfate radicals (SO4•−) with respect to •OH. The results showed that the single-crystal BDD significantly promoted •OH formation but also that the interactions between boron doping, current density and anolyte concentration determined the underlying degradation mechanisms. Therefore, this study demonstrated that characterising the BDD material and understanding its interactions with other process operating conditions prior to degradation experiments is a crucial step to attain the optimisation of any wastewater treatment application.

First-principles investigation of Boron-doped graphene/MoS2 heterostructure as a potential anode material for Mg-ion battery

In this work, the potential of boron-doped graphene/MoS2 (Gr/MoS2) as an anode material for magnesium ion batteries was investigated using density functional theory (DFT) based on first-principles calculations. It’s found that the adsorption capacity gradually increases (−3.078 eV) with the increase in the number of doped-boron atom. Due to the lower electronegativity of boron atom (2.04) compared to carbon atom (2.55), electrons can be transferred from boron atom to neighboring carbon atoms, resulting in positively charged boron atom. Boron doping introduces p-type doping, which increases the number of holes in the substrate and raises the carrier concentration. The energy of the density of states near the Fermi level also increases with the increase of boron-doping concentration, indicating its excellent electronic conductivity. When the number of boron atoms reaches four, the barriers of the two diffusion paths reduce to 0.49 eV and 1.025 eV, respectively. Simultaneously, the theoretical magnesium storage capacity increases to 147.26 mAh g−1. Our research results demonstrate that boron-doping significantly enhances the adsorption and storage performance of Mg, providing a theoretical basis for the investigation of anode materials for magnesium ion batteries.

Direct growth of few-layered graphene on boron doped diamond surface with varying boron doping concentration

The diamond-graphene heterostructure is a promising all‑carbon composite structure, which can take advantages of excellent properties of these two materials. At present, the diamond-graphene heterojunction were mostly synthesized by chemical vapor deposition (CVD) method with intrinsic diamond substrate. In this study, the few-layered graphene is synthesized on boron-doped-diamond (BDD) surface through a simple thermal treatment method with Ni catalyst. The effects of boron doping concentration of substrate on the synthesis of diamond-graphene heterojunctions is studied. It demonstrates that the surface morphology and roughness are improved with the increasing of substrate doping concentration. Compared with the light doped and un-doped diamond, the number of graphene layers and quality decreases and increases, respectively.

Bottom-up strategy of multi-level structured boron-doped diamond for the durable electrode in water purification

Long-term exposition of electrodes to aqueous media inevitably results in biofouling and adhesion of bacteria, reducing the electrolysis efficiency of electrodes for water treatment. To ensure technically efficient antifouling of materials for durable electrodes, hierarchical micro-/nano structured boron-doped diamond (BDD) electrodes were designed and synthesized. Multi-level structured BDD was coated on titanium mesh by a bottom-up strategy, based on a combination of self-assembly seeding and hot filament chemical vapor deposition (HFCVD) growth. The morphology of the BDD coating can be controlled by manipulating the seeding density and boron doping concentration. The designed micro/nano hierarchical structure of the BDD electrode suppressed bacterial adhesion greatly and exhibited excellent anti-biofouling efficiency with an antibacterial rate of ∼ 93 %, which entails simplified self-cleaning and durable BDD-coated electrodes. The BDD-coated electrodes were employed to electrochemically treat Escherichia coli-contaminated water, killing virtually all bacteria (≥99.9 %) in 1 min. Finally, real river water was electrochemically treated, reducing the chemical oxygen demand (COD) down to 5 mg/L in 4 h. The excellent performance shows the great potential of the structured BDD electrodes for long-term water purification.

The effect of boron co-doping on thermoluminescence and optically stimulated luminescence properties of LiMgPO4:Tb,Sm

The effect of boron co-doping on optically stimulated luminescence (OSL) and thermoluminescence (TL) properties of LiMgPO4:Tb,Sm,B prepared by solid-state reaction was studied. The structure of the prepared materials was confirmed by X-ray diffraction. The TL glow curves of samples irradiated with different doses of β rays were tested. No matter how much B is doped, the peaks at 190 or 280 °C are for a first-order kinetic glow curve. The activation energy and frequency factor remained almost unchanged with the increase of boron doping concentration, which indicated the trap centers of LiMgPO4:Tb,Sm,B were independent of boron doping concentration. The E at 190 and 280 °C are around 1.16 eV and 1.55 eV. Photo-ionization cross-section showed significant changes and the sensitivity of OSL reached a maximum for a concentration of 4 mol% with increasing of boron doping concentration. B-doping enhanced the OSL-signal with a factor 2.6 when B concentration is 4 mol%. The repeatability of the powders for OSL were also studied and the relative standard deviation was less than 1.5%. The minimal detectable dose (MDD) of LiMgPO4:Tb,Sm,B with a boron doping concentration of 4 mol% was 8.2 μGy. This material has a fast decay time, good repeatability, low MDD and has further research value.

Arc discharge synthesis of graphene with enhanced boron doping concentration for electrochemical applications

The physicochemical properties of graphene, such as the bandgap and electrical conductivity, can be tuned when the carbon atoms are replaced with other heteroatoms. In addition to nitrogen, boron is a dopant that can compensate for the properties lacking in graphene; however, boron-doped graphene has not received significant attention owing to its low doping rate. In this study, we report an improvement in the doping efficiency of arc graphene by utilizing a boron precursor and graphene oxide as anode carbon fillers. X-ray photoelectron spectroscopy revealed that the doping level of the synthesized graphene flakes (5.7at.%) was significantly higher than that of boron-doped arc graphene reported in the literature (3at.%). Cyclic voltammetry, electrochemical impedance spectroscopy, and constant-current charge/discharge experiments were performed to investigate the electrochemical properties of boron-doped graphene. The synthesized boron-doped graphene exhibited an areal capacitance of 66 μF cm−2, which is superior to that of other doped carbon materials. The electrochemical activity of boron-doped graphene is affected more by functionalized doping than by substitutional doping, because of the improved wettability displayed by the former. Boron-doped graphene flakes required for various applications can be easily obtained by arc discharge synthesis.

Boron-doped amorphous carbon deposited by DC sputtering for a hardmask: Microstructure and dry etching properties

Boron-doped amorphous carbon (a-C) films have been investigated as a hardmask material for improving semiconductor integration, deposited using direct current (DC) magnetron sputtering with varying boron concentrations. Increased boron doping concentration in a-C led to a higher etch resistance but also resulted in the gradation of etch resistivity in the depth direction of the film, as confirmed by a continuous dry etching process. Scanning transmission electron microscopy electron energy loss spectroscopy showed an increase in the sp3 ratio of the film owing to boron doping as well as gradation in the B K edge region of a film doped with a high concentration of boron. This is because the high reactivity between boron and oxygen results in the reaction of residual oxygen in the chamber with boron. Time-of-flight secondary ion mass spectrometry was used to evaluate the penetration resistance to fluorine ions in the dielectric etchant. The results confirmed that B-O bonding resulted in relatively low fluorine resistance. Boron bonded with carbon can significantly improve the dry etch performance; however, bonding with oxygen needs to be effectively controlled to realize desirable film properties. Overall, this study demonstrates the potential of boron-doped a-C films as a hardmask material for the semiconductor industry.

Front-side releasing oriented clamped–clamped beams for piezoresistive sensors

Front-side releasing suspended structures made using bulk micromachining processes have the advantages of simplifying vacuum or hermetic packaging processes and reducing squeeze-film damping. This paper studies the effect of doping concentration on the etching rate (ER) of the (111) plane. The experimental results show that increasing the boron doping concentration (but to less than the self-stop etching concentration) significantly increases the ER of the (111) plane and the ER ratio of the (111) and (100) planes. This phenomenon is used to speed up the undercutting and release <110> oriented clamped–clamped beams, which can be used as piezoresistive sensitive elements. The etching depth when the microbeams have just been released and the silicon wedges under single beams, double beams and triple beams disappear is deduced and verified by experiments. This has a certain guiding significance for designing piezoresistive sensors.

Effect of Boron Doping Concentration on the Wettability and Surface Free Energy of Polycrystalline Boron-Doped Diamond Film

The wettability and surface free energy of diamonds are crucial for their applications. In this study, polycrystalline boron-doped diamond (PBDD) films with different boron doping concentrations were prepared, and the effect of the boron doping concentration on the wettability and surface free energy (SFE) of the film was investigated. The SFEs of the PBDD films were investigated by employing the surface tension component approach and the equation-of-state approach. The investigation suggested that the alternative formulation of Berthelot’s rule, the Lifshitz-van der Waals/acid-base (van Oss) approach, and the Owens-Wendt-Kaelble approach were suitable for estimating the SFEs of PBDD films, whereas the Fowkes approach, Berthelot’s (geometric mean) combining rule, and Antonow’s rule could not provide reliable results. Results showed that the SFEs of PBDD films increased with increasing boron doping concentration, and the SFEs were 43.26–49.66 mJ/m2 (Owens-Wendt-Kaelble approach), 42.89–52.26 mJ/m2 (Lifshitz-van der Waals/acid-base), and 44.38–48.73 mJ/m2 (alternative formulation of Berthelot’s rule). This study also provides a reference for the application of empirical and physics-based semi-empirical approaches to SFE estimation.

Surface treatment technology of downhole water cut sensor

Based on the structure, working principle, and working conditions of conductance water cut sensor, it is revealed that the early failure of the metal electrode of the sensor is due to the comprehensive influence of well fluid erosion, electrochemical corrosion, and oil pollution during its long-term service in the downhole. A technology for electrode surface treatment is proposed using boron-doped diamond (BDD) films to improve the service performance of the modified electrode. The hot wire chemical vapor deposition method was adopted to fabricate BDD film, the boron doping concentration and deposition time were optimized, and fluorination treatment was applied to improve the wear resistance, electrochemical corrosion resistance, and oleophobic property of the BDD film comprehensively. The results showed that BDD film with boron doping concentration of 6×10-3 exhibited high wear resistance and good electrochemical corrosion resistance, and endowed the modified electrode with superior erosion resistance and corrosion resistance. The friction coefficient and wear rate of BDD modified electrode were 92% and 78% lower than those of Invar alloy, also, the low-frequency impedance modulus value of the modified electrode was higher than 1×104 Ω·cm2. The BDD film prepared with a deposition time of 8 h had a favorable micro-nano structure owing to small grain size and uniform distribution. Such morphology was conducive to enhancing the oleophobic performance of the modified electrode, and its contact angle in the simulated well fluid was high to 102°. The engineering applicability of BDD film modified electrode under simulated working conditions indicated that, the modified electrode had excellent comprehensive performances of erosion resistance, electrochemical corrosion resistance and oil adhesion resistance, and can realize the long-term stable operation of the conductance water cut sensor under harsh downhole conditions.

Effects of Boron Doping on the Bulk and Surface Acoustic Phonons in Single-Crystal Diamond.

We report the results of the investigation of bulk and surface acoustic phonons in the undoped and boron-doped single-crystal diamond films using the Brillouin-Mandelstam light scattering spectroscopy. The evolution of the optical phonons in the same set of samples was monitored with Raman spectroscopy. It was found that the frequency and the group velocity of acoustic phonons decrease nonmonotonically with the increasing boron doping concentration, revealing pronounced phonon softening. The change in the velocity of the shear-horizontal and the high-frequency pseudo-longitudinal acoustic phonons in the degenerately doped diamond, as compared to that in the undoped diamond, was as large as ∼15% and ∼12%, respectively. As a result of boron doping, the velocity of the bulk longitudinal and transverse acoustic phonons decreased correspondingly. The frequency of the optical phonons was unaffected at low boron concentration but experienced a strong decrease at the high doping level. The density-functional-theory calculations of the phonon band structure for the pristine and highly doped samples confirm the phonon softening as a result of boron doping in diamond. The obtained results have important implications for thermal transport in heavily doped diamond, which is a promising material for ultra-wide-band-gap electronics.

Conductive printable electrodes tuned by boron-doped nanodiamond foil additives for nitroexplosive detection

An efficient additive manufacturing-based composite material fabrication for electrochemical applications is reported. The composite is composed of commercially available graphene-doped polylactide acid (G-PLA) 3D printouts and surface-functionalized with nanocrystalline boron-doped diamond foil (NDF) additives. The NDFs were synthesized on a tantalum substrate and transferred to the 3D-printout surface at 200 °C. No other electrode activation treatment was necessary. Different configurations of low- and heavy-boron doping NDFs were evaluated. The electrode kinetics was analyzed using electrochemical procedures: cyclic voltammetry and electrochemical impedance spectroscopy. The quasi-reversible electrochemical process was reported in each studied case. The studies allowed confirmation of the CV peak-to-peak separation of 63 mV and remarkably high heterogeneous electron transfer rate constant reaching 6.1 × 10−2 cm s−1 for 10 k ppm [B]/[C] thin NDF fitted topside at the G-PLA electrode. Differential pulse voltammetry was used for effective 2,4,6-trinitrotoluene (TNT) detection at the studied electrodes with a 87 ppb limit of detection, and wide linearity range between peak current density and the analyte concentration (0.064 to 64 ppm of TNT). The reported electrode kinetic differences originate primarily from the boron-dopant concentration in the diamond and the various contents of the non-diamond carbon phase.Graphical abstract

Electrochemical properties and morphology of boron-doped diamond thin films

A boron-doped diamond (BDD) thin film was synthesized using the hot filament chemical vapor deposition (HFCVD) method. The surface shape, growth rate, bonding structure, and electrochemical properties of the BDD thin films were estimated through scanning electron microscopy (SEM), Raman spectroscopy, and cyclic voltammetry. As the boron doping concentration increased, the growth rate and crystal size of the diamond thin film decreased. Through Raman analysis, it was confirmed that the 1332 cm[Formula: see text] peak of diamond gradually became less intense, and peaks were generated at 480 cm[Formula: see text] and 1220 cm[Formula: see text] due to the bonding of boron to carbon. Cyclic voltammetry analysis of the BDD thin film showed a large potential window with a width of approximately 2.8 V. The highest applied voltage (2 V) versus response current (0.02 A) was obtained at a B/C ratio of 2000 ppm.

Impact of Boron Doping Concentration on Tunnel Oxide Passivated Contact in Front Surface for N-Type Poly-Si Based Passivated Contact Bifacial Solar Cells

This article reports on a novel bifacial tunneling oxide passivated contact n-PERT bifacial c-Si solar cell structure. This cell uses bifacial tunneling oxide passivated contact structures on the front and rear surfaces. The analysis focuses on the impact of the boron doping concentration on the passivation performance of the tunneling oxide passivated contact structures on the front surface. The simulations were performed with boron doping concentration > 1E20 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> , Silicon dioxide layer thickness > 0.9 nm, and Silicon dioxide layer quality (interface-states density <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">it</sub> = 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> /eV and pinhole density <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ph</sub> < 1 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−4</sup> ) for Silicon dioxide layer at boron doping concentration of 1E20 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> . Implied open circuit voltage ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iV</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oc</sub> ) and recombination current density ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">oe</sub> ) reaches up to 729 mV and 8.62 fA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D_n</i> = 5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). The open-circuit voltage of the prepared bifacial tunnel oxide passivated contact solar cell with a large area of 252 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> reaches up to 704.5 mV. The average conversion efficiency is 22.08%, which is 0.15% higher than that of the solar cell with traditional PERT structure on the front side and tunneled oxide passivated contact on the rear side. The main factors limiting the efficiency improvement of this structured cell are the parasitic absorption of light by the front surface polysilicon and the minority carrier lifetime of the silicon wafer. By simulating and optimizing, the highest conversion efficiency of the cell can reach 24.38% and the open-circuit voltage of the cell can reach 727.4 mV.

Electrochemical oxidation of landfill leachate using boron-doped diamond anodes: pollution degradation rate, energy efficiency and toxicity assessment.

Electrochemical oxidation (EO), due to high efficiency and small carbon footprint, is regarded as an attractive option for on-site treatment of highly contaminated wastewater. This work shows the effectiveness of EO using three boron-doped diamond electrodes (BDDs) in sustainable management of landfill leachate (LL). The effect of the applied current density (25-100mAcm-2) and boron doping concentration (B/C ratio: 500ppm, 10,000ppm and 15,000ppm) on the performance of EO was investigated. It was found that, of the electrodes used, the one most effective at COD, BOD20 and ammonia removal (97.1%, 98.8% and 62%, respectively) was the electrode with the lowest boron doping. Then, to better elucidate the ecological role of LLs, before and after EO, cultivation of faecal bacteria and microscopic analysis of total (prokaryotic) cell number, together with ecotoxicity assay (Daphnia magna, Thamnocephalus platyurus and Artemia salina) were combined for the two better-performing electrodes. The EO process was very effective at bacterial cell inactivation using each of the two anodes, even within 2h of contact time. In a complex matrix of LLs, this is probably a combined effect of electrogenerated oxidants (hydroxyl radicals, active chlorine and sulphate radicals), which may penetrate into the bacterial cells and/or react with cellular components. The toxicity of EO-treated LLs proved to be lower than that of raw ones. Since toxicity drops with increased boron doping, it is believed that appropriate electrolysis parameters can diminish the toxicity effect without compromising the nutrient-removal and disinfection capability, although salinity of LLs and related multistep-oxidation pathways needs to be further elucidated.

Effects of the doping concentration of boron on physicochemical, mechanical, and biological properties of hydroxyapatite

Ion doping is an approach to modify properties of materials, like hydroxyapatite (HA), that contributes to designing biomaterials with desired characteristics applicable in bone defect treatments. Recently, boron (B) has been noticed in biomaterial fields due to its beneficial effects on formation, growth, and quality of bone. In this study, B-doped HA nanoparticles with different molar concentrations of B (0.05, 0.1, 0.25, and 0.5) were synthesized through microwave-assisted wet precipitation. The effects of B content on various properties of HA were evaluated. The results demonstrated that the size of HA particles reduced from 106 nm to 89-85 nm in B doped materials. Meanwhile, the crystallinity degree of B doped HA (BHA) samples was between 89.90% and 93.77%, compared to 95.19% of HA. Diametral tensile strength of samples was measured in the ranges of 2.51 and 3.61 with no significant difference among groups. The micro-hardness of HA was 0.88 GPa, whilst doped ones had hardness values of 0.5 GPa–0.68 GPa. Biodegradability of samples increased from less than 1% to approximately 4% after 28 days, while B-doping did not make any change in the degradation rate. Doping dosages were appropriate in terms of bioactivity and cell viability, and B doping caused higher bioactivity and cell proliferation. All changed properties were dose-dependent and more effective in doped groups with a higher amount of B. Despite proliferative effect, 260 μg/l and 770 μg/l of B release in two groups with the highest dopant concentrations did not positively influence the osteogenic activity of cells. Our results demonstrated that doping concentrations that resulted in B release ≤260 μg/l seem more appropriate dosage, especially for bone tissue engineering and substitute applications due to promoted bioactivity and proliferation, as well as no obstructive effects on mechanical properties and osteogenic activities of HA.

Boron Detection Technique in Silicon Thin Film Using Dynamic Time of Flight Secondary Ion Mass Spectrometry

The impurity concentration is a crucial parameter for semiconductor thin films. Evaluating the impurity distribution in silicon thin film is another challenge. In this study, we have investigated the doping concentration of boron in silicon thin film using time of flight secondary ion mass spectrometry in dynamic mode of operation. Boron doped silicon film was grown on i) p-type silicon wafer and ii) borosilicate glass using hot wire chemical vapor deposition technique for possible applications in optoelectronic devices. Using well-tuned SIMS measurement recipe, we have detected the boron counts 101~104 along with the silicon matrix element. The secondary ion beam sputtering area, sputtering duration and mass analyser analysing duration were used as key variables for the tuning of the recipe. The quantitative analysis of counts to concentration conversion was done following standard relative sensitivity factor. The concentration of boron in silicon was determined 1017~1021 atoms/㎤. The technique will be useful for evaluating distributions of various dopants (arsenic, phosphorous, bismuth etc.) in silicon thin film efficiently.

Effect of Boron Doping Level on BDD Electrode for Heavy Metal Ion Sensor

Recently, industrial wastewater is being discharged in large quantities due to the development of industry and this wastewater contains a various heavy metal ion. Exposure to high levels of trace metal ions [Cd (II), Pb (II), Cu (II)] causes a variety of health and environmental problems. These toxic species accumulated in the human body through the water source have a low rate of clearance. [1,2]To minimize the exposure of humans to these contaminants through effective water quality monitoring, anode stripping voltammetry (ASV) method was used. ASV method has wide linear dynamic range, low detection limit (ppb), multi-element analysis capability and the simplicity of the instrumentation, which is relatively inexpensive and small in size, requires low levels of electrical power and is sufficiently portable to permit its use in the field. So, ASV has been used successfully for the determination of heavy metals in water. The sensitivity of differential pulse anode stripping voltammetry (DPASV) is higher than other classical voltammetry, because of its enhanced faradaic current and decreased non-faradaic charging current. [2]In generally, Ir, Au, Ag and Hg electrodes have been used for stripping analysis of trace metals, but the Ir, Au, Ag electrodes have low sensitivity, Hg electrode have toxicity and volatility. [2] To solve this drawbacks, we fabricate a Boron-doped diamond (BDD) electrodes. BDD electrodes are candidate for use in the detection of a trace heavy metal ions, because these show good electrical conductivity, low background current, and non-toxicity.In this study, BDD electrodes on Si substrate deposited by hot filament chemical vapour deposition (HFCVD) and applied to DPASV measurement. Through the optimization of the deposition condition of BDD electrodes and measurement condition of DPASV, we increased the detection sensitivity of heavy metal ions. The BDD electrode with the optimum boron doping concentration by controlling the boron doping concentration from 100 to 10000 ppm in the deposition process optimization step has excellent durability and selectivity of heavy metal ions. As a result of electrochemical measurement, BDD electrode with 8000 ppm B was displayed high sensitive response and wide potential window range of -1.7 V to 1.6 V with the detection limit of 0.001 mg/L to 0.01 mg/L ±5 % about heavy metal ions [Cd (II), Pb (II), Cu (II)].[1] M.O. Park et al, Electroanalysis. 2017, 29, pp. 514 – 520[2] J. –H. Yoon et al, Bull. Korean Chem. Soc. 2010, Vol. 31, No. 1This study was supported by the Korea Environmental Industry & Technology Institute[grant number 20190027400012] and R&D Center for Green Patrol Technologies through R&D for Global Top Environmental Technologies [grant number 20180018400013] funded by the Ministry of Environment, Republic of Korea (MOE), Figure 1