Implantation Of Bi Research Articles

In Situ Implantation of Bi2S3 Nanorods into Porous Quasi-Bi-MOF Architectures: Enabling Synergistic Dissociation of Borohydride for an Efficient and Fast Catalytic Reduction of 4-Nitrophenol.

Catalytic hydrogenation reduction based on sodium borohydride (NaBH4) has gained attention as an appealing "one-stone-two-birds" approach for the simultaneous elimination of nitroaromatic pollutants and the production of high-value aminoaromatics under mild conditions. However, the slow kinetics of NaBH4 dissociation on the surface of catalysts restrict the catalytic hydrogenation reduction efficiency. Herein, we report an intelligent localized sulfidation strategy for an in situ implantation of Bi2S3 nanorods within quasi-Bi-MOF architectures (Bi2S3@quasi-Bi-MOF) by fine-tuning the pyrolysis temperature. In this novel Bi2S3@quasi-Bi-MOF, the porous quasi-Bi-MOF enables efficient adsorption of BH4- and 4-nitrophenol (4-NP), while Bi2S3 facilitates the BH4- dissociation to form Hads* species adsorbed on the catalyst surface. Benefiting from the synergistic structure, Bi2S3@quasi-Bi-MOF exhibits excellent performance for the catalytic reduction of 4-NP, delivering a high turnover frequency (TOF) of 1.67 × 10-4 mmol mg-1 min-1 and an extremely high normalized rate constant (knor) of 435298 s-1 g-1. The kinetic analysis and electrochemical tests indicate that this catalytic hydrogenation reduction follows the Langmuir-Hinshelwood mechanism. This study enriches the synthetic strategy of MOF-based derivatives and offers a new catalytic platform for hydrogenation reduction reactions.

Effect of bismuth ion implantation on the crystallization temperature of the amorphous Ge2Sb2Te5 thin films

Bismuth doped Ge2Sb2Te5 thin films were prepared by magnetron sputtering of Ge2Sb2Te5 target with following ion implantation of Bi. Thin film compositions and elemental distribution across the film thicknesses were determined. An amorphous state of the as-deposited undoped and Bi-doped Ge2Sb2Te5 thin films was confirmed by X-ray diffraction. Temperature dependencies of the resistivity for Bi-doped Ge2Sb2Te5 thin films were measured. Two resistivity drops due to the crystallization and transformation from the cubic to hexagonal structure were determined. Decreases of the onset temperatures for the first and second transitions from 169.3 to 120.3 °C and from 188.0 to 153.0 °C with the increase of Bi concentration were found. It was shown, that the resistivity of the amorphous films sufficiently decreases with Bi concentration, while the variation of resistivity for the crystallized state is much smaller.

Bi@Bi4Ti3O12/TiO2 films on glass with photocatalytic and self‐cleaning performance

AbstractA stable and translucent Bi@Bi4Ti3O12/TiO2 film was fabricated on conventional glass substrates for the first time. The film exhibited a good photocatalytic performance and efficient self‐cleaning capability against organic dyes under full spectral irradiation and visible light irradiation. Bi4Ti3O12/TiO2 film was first prepared on a glass substrate with colloidal silica as a high temperature binder, followed by implantation of nanoscale Bi in it by an in‐situ partially reduction of Bi4Ti3O12 to generate Bi@Bi4Ti3O12/TiO2 films. The improved photocatalytic ability is probably attributed to the surface plasmon resonance of Bi atom as well as the enhanced electron transfer efficiency and synergistic effect of Bi4Ti3O12 and TiO2. According to trapping experiments, hydroxyl radicals (OH) were active species in the photocatalytic degradation of dyes under full spectral light irradiation and possible photocatalytic mechanism was proposed. The film prepared in this work may well have potential practical applications in many aspects, such as cleansing treatments for high building external decorative panels and also systematic characterization of the film suggests that the in‐situ reduction is an effective and simple way to produce nanoscale Bi@Bi4Ti3O12.

Сравнение зрительных функций у пациентов после имплантации бифокальных, трифокальных и монофокальных интраокулярных линз

The widespread implantation of bifocal and trifocal Intraocular lenses (IOL) in the cataract surgery provides patients with a visual independence, however, at the same time some optical phenomena associated with the inner structure of multifocal IOLs may appear, that negatively affect functional results of cataract surgery. Therefore, a comparison of patients’ visual functions after implantation of tri-, bi- and mono-focal intraocular lenses seems topical. Purpose . To compare pseudo-accommodation abilities, contrast sensitivity, satisfactory subjective perception of cataract patients after implantation of refractive-diffractive bi-, tri- and mono-focal IOLs. Material and methods. This study included 150 patients (150 eyes). They were divided into three groups depending on the type of implanted lens: bifocal IOL (45 patients), trifocal IOL (45 patients), mono-focal IOL (the control group, 60 patients). Ultrasound cataract phacoemulsification with IOL implantation was performed in one eye of each patient. Patients were examined for the visual acuity at different distances and the contrast sensitivity function, as well as the subjective satisfaction was evaluated using a questionnaire. Results . An improved distance visual acuity was noted in all research groups, the near visual acuity was higher for implanted bi- and trifocal IOLs (0.64±0.09 and 0.61±0.10, respectively) compared with the mono­focal IOL (0.36±0.07), the visual acuity at medium distances was better for trifocal IOLs (0.61±0.14). The contrast sensitivity function was higher in the mono-focal IOL group. Therewith, the subjective satisfaction was higher for multifocal IOLs compared to mono-focal IOLs. It was revealed that such negative optical phenomena as glares and halos appeared more often after trifocal IOLs implantation (68.2%). The application of spectacles was required in patients of the bifocal IOL group in 22.1% of cases, in the trifocal IOL group in 17.9% of cases and in the mono-focal IOL group in 70.1% of cases. Conclusion . Implantation of multifocal IOLs compared to mono­focal IOLs provides a better pseudo-accommodation function and higher degrees of visual independence and subjective satisfaction compared to mono-IOL. This is offset by a higher frequency of optical phenomena negatively affecting the obtained functional results.

Spin-orbit coupling induced by bismuth doping in silicon thin films

This study demonstrates an enhancement of spin-orbit coupling in silicon (Si) thin films by doping with bismuth (Bi), a heavy metal, using ion implantation. Quantum corrections to conductance at low temperatures in phosphorous-doped Si before and after Bi implantation are measured to probe the increase in spin-orbit coupling, and a clear modification of magnetoconductance signals is observed: Bi doping changes magnetoconductance from weak localization to the crossover between weak localization and weak antilocalization. The elastic diffusion length, phase coherence length, and spin-orbit coupling length in Si with and without Bi implantation are estimated, and the spin-orbit coupling length after Bi doping becomes the same order of magnitude (Lso = 54 nm) with the phase coherence length (Lφ = 35 nm) at 2 K. This is an experimental proof that spin-orbit coupling strength in the thin Si film is tunable by doping with heavy metals.

Electron conductivity in GeTe and GeSe upon ion implantation of Bi

This paper presents results on ion implantation of bismuth in GeTe and GeSe films. The conductivity and the thermopower of amorphous chalcogenide films are investigated. Electron conductivity in the films is attained at the Bi implantation doses higher than (1.5–2) × 1016 cm−2. In conjunction with the structural modification in the films as revealed Raman spectroscopy, the results suggest the structural re-arrangement of the amorphous network occurs via weakening the bonds of a lower energy. The onset of electron conductivity is hindered by a stronger bond in an alloy. In GeTe, this is the Ge-Ge bond.

Electrical properties of Bi-implanted amorphous chalcogenide films

The impact of Bi implantation on the conductivity and the thermopower of GeTe, Ge–Sb–Te, and Ga–La–S films is investigated. The enhanced conductivity appears to be notably sensitive to a dose of an implant. Incorporation of Bi in amorphous chalcogenide films at doses up to 1×1015 cm−2 is seen not to change the majority carrier type and activation energy for the conduction process. Higher implantation doses may reverse the majority carrier type in the studied films. Electron conductivity was observed in GeTe films implanted with Bi at a dose of 2×1016 cm−2. These studies indicate that native coordination defects present in amorphous chalcogenide semiconductors can be deactivated by means of ion implantation. A substantial density of implantation-induced traps in the studied films and their interfaces with silicon is inferred from analysis of the space-charge-limited current and capacitance-voltage characteristics taken on Au/amorphous chalcogenide/Si structures.

Influence of Bi on embedded nanocrystal formation and thermoelectric properties of GaAs

We have examined the influence of Bi on embedded nanocomposite formation and the resulting thermoelectric properties of GaAs. Bi implantation amorphizes the GaAs matrix, reducing both the free carrier concentration (n) and the electrical conductivity (σ). Following rapid thermal annealing, the matrix is transformed to single crystal GaAs with embedded Bi nanocrystals (NCs). In comparison to a GaAs reference, the Bi NC-containing films exhibit a sizeable reduction in thermal conductivity (κ), leading to a 30% increase in the thermoelectric figure-of-merit. We also present a universal trend for the influence of microstructure on the n-dependence of σ and κ.

N-type chalcogenides by ion implantation.

Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary difficulty in obtaining n-type conductivity. The ability to form chalcogenide glass p-n junctions could improve the performance of phase-change memory and thermoelectric devices and allow the direct electronic control of nonlinear optical devices. Previously, carrier-type reversal has been restricted to the GeCh (Ch=S, Se, Te) family of glasses, with very high Bi or Pb 'doping' concentrations (~5-11 at.%), incorporated during high-temperature glass melting. Here we report the first n-type doping of chalcogenide glasses by ion implantation of Bi into GeTe and GaLaSO amorphous films, demonstrating rectification and photocurrent in a Bi-implanted GaLaSO device. The electrical doping effect of Bi is observed at a 100 times lower concentration than for Bi melt-doped GeCh glasses.

Exploring the surface sensitivity of TOF-secondary ion mass spectrometry by measuring the implantation and sampling depths of Bi(n) and C60 ions in organic films.

The surface sensitivity of Bi(n)(q+) (n = 1, 3, 5, q = 1, 2) and C(60)(q+) (q = 1, 2) primary ions in static time-of-flight secondary ion mass spectrometry (TOF-SIMS) experiments were investigated for molecular trehalose and polymeric tetraglyme organic films. Parameters related to surface sensitivity (impact crater depth, implantation depth, and molecular escape depths) were measured. Under static TOF-SIMS conditions (primary ion doses of 1 × 10(12) ions/cm(2)), the 25 keV Bi(1)(+) primary ions were the most surface sensitive with a molecular escape depth of 1.8 nm for protein films with tetraglyme overlayers, but they had the deepest implantation depth (~18 and 26 nm in trehalose and tetraglyme films, respectively). The 20 keV C(60)(+2) primary ions were the second most surface sensitive with a slightly larger molecular escape depth of 2.3 nm. The most important factor that determined the surface sensitivity of the primary ion was its impact crater depth or the amount of surface erosion. The most surface sensitive primary ions, Bi(1)(+) and C(60)(+2), created impact craters with depths of 0.3 and 1.0 nm, respectively, in tetraglyme films. In contrast, Bi(5)(+2) primary ions created impact craters with a depth of 1.8 nm in tetraglyme films and were the least surface sensitive with a molecular escape depth of 4.7 nm.

The influence of krypton and bismuth–krypton implantation on manganin sensitivity to temperature and hydrostatic pressure

The influence of implantation of krypton ions and the combined implantation of bismuth and krypton ions into manganin pressure sensors on their sensitivity to pressure and temperature has been investigated. Manganin pressure sensors were of the foil type, 10 μm thick, and of relatively large planar dimensions. Implanted dose of Kr was 2.5×1015 ion/cm2 with the energy of 245 MeV/ion. In the case of combined implantation, it was as high as 1016 ion/cm2 with the energy of ∼255 keV/ion for Bi ions and 1017 ion/cm2 with the energy of ∼255 keV/ion for Kr ions. Implantation of high-energy Kr ions makes the pressure sensitivity increase only ∼1%, but for the complex Kr–Bi implantation, the increase of pressure sensitivity by 25% has been observed. Modelling of the resistance properties of the sensor, representing it as a parallel connection of strongly implanted and almost not implanted parts, allowed us to estimate the increase in the pressure sensitivity of the strongly implanted part as being much higher (∼250%). High-dose implantation with Kr and Bi ions remarkably changes the temperature-resistance characteristic of manganin sensor, making it more convenient for the use in the vicinity of room temperature. The surface structure of the manganin foil after high-energy Kr ions implantation has smaller roughness.

Diffusion of Bi, Er and Eu implanted into S1813 photoresist

We report on the diffusion of Bi, Er and Eu in the photoresist S1813. The implantation of Bi into the resist at low energies ( E=20 keV) and fluences ( Φ=10 12 cm −2) allowed us to minimize both radiation damage and cluster formation. The impurity redistribution in the samples annealed between 100 and 300 °C was determined using the Rutherford backscattering technique. The results for Bi indicate regular thermal diffusion with an activation energy of E a=680 meV. At higher fluences, the trapping in radiation-induced defects influence the migration behavior. However, the activation energy is hardly influenced (650 meV for implanted Bi at 5 × 10 12 cm −2). Both the lanthanides Er and Eu implanted into the resist at fluences of 5 × 10 12 and 10 13 at/cm 2 show quite a similar behavior as Bi implanted at the highest fluence with similar values for the activation energy ( E a(Eu)=525 meV and E a(Er)=530 meV).

Lattice location of bismuth implanted into beryllium single crystals

Bi ions have been implanted into <112¯> Be single crystals at T=5.5, 77 and 293 K using doses between 1 × 10 14 atoms/cm 2 and 1.3×10 15 atoms/cm 2 and an ion energy of 300 keV. In situ Rutherford backscattering (RBS) and channeling with 1.5 MeV He ions was used to determine the lattice location of the implanted species. For low dose implantation at 293 K we observed occupation of octahedral interstitial sites. With increasing dose the octahedral fraction decreased and a random distribution of Bi atoms was observed. By postimplantation of Mn, Bi shifted back to octahedral sites, while Mn was totally substitutional. In all cases a depth dependence of the octahedral fraction was observed being larger in near surface regions. Implantation of Bi at 5.5 K resulted a substitutional fraction of f s = 0.2, together with a random fraction. No change was observed after warming up to 77 K; however upon warming up to 293 K, Bi shifted to octahedral sites. Implantation of Bi at 77 K resulted in f s values similar to those for 5.5 K implantation. The shift of Bi atoms from random to octahedral sites during postimplantation and annealing and also the depth dependence of the octahedral fraction are attributed to the interaction of Bi atoms with vacancies (V) forming BiV χ complexes and especially BiV 6 for Bi on octahedral sites.

Amorphous-crystal boundary motion and impurity redistribution during keV Ne + ion irradiation of Si

Thin (approximately 400 Å) amorphous layers extending inwards from the surface were produced in Si by either Sb, Bi or Xe implantation. These layers were then subjected to further irradiation with 20, 40 or 80 keV Ne + ions at selected fixed temperatures in the range of 77 to 670 K and with a range of ion flux densities over two orders of magnitude. At high temperatures amorphous-crystal interface annealing occurs whilst at low temperatures a balance can be found between these competing processes and the critical temperature for interface stasis is observed to be a function of ion flux density. The data allows evaluation of activation energies for radiation-assisted annealing and for the steady state balance process to be deduced and these are found to be in close agreement with earlier, similar studies employing MeV ion irradiation. The nature of the initial impurity (Sb, Bi or Xe) was found to mediate the recrystallisation process and in all impurity cases their depth redistribution during Ne + irradiation was also observed. This redistribution appears to be correlated to the advance of the interface. These results are compared with earlier studies using thermal annealing only.

Thermal stability and diffusion studies in the Au and Bi implanted AZ1350 photoresist

The thermal stability of Au and Bi implanted AZ1350 photoresist films has been investigated via Rutherford backscattering spectrometry. It is observed that the unimplanted photoresist starts to decompose at 200°C. A shallow implantation of Bi and Au produces similar damage in the film but only the Bi implanted sample displays a marked improvement in the thermal stability (up to 350°C). This indicates that, besides radiation damage, chemical effects also play a role in the improvement of the photoresist's thermal stability. The thermal behaviour of Au and Bi implanted in the photoresist has also been studied. It was found that Bi diffuses regularly while Au follows an irregular diffusion process.

Implantation and thermal annealing behaviour of Bi imlanted into the Al/KCl bilayer compound

Abstract A bilayer system composed of an Al 610 A film evaporated onto a KCl single crystal and a pure KCl single crystal were both implanted with 300 keV 209Bi+. The Bi depth distribution agrees with the Monte-Carlo simulation predictions in both systems. Diffusion of Bi in the Al film and in the KCl substrate of the Al/KCl system, as well as in the pure KCl crystal, is studied as a function of isochronal annealing. For low temperatures up to 200°C we observe enhanced diffusion of Bi in all systems. At higher temperatures (up to 500°C) a regular diffusion governs the depth profiles.

Implantation and thermal annealing behaviour of Bi implanted into Al/Ti and Al/V bilayer structures

Two bilayer systems, (Al(1500 Å)/Ti and Al(500 Å)/V systems) were implanted with Bi at energies of 600 and 150 keV, respectively. The implanted depth distributions are in both systems very well reproduced by calculations using the Monte Carlo TRIM simulation method. After anneal up to 400°C (Al/Ti) and 550°C (Al/V) the depth profiles still resemble the as-implanted ones. It is concluded that the interface region acts as a trapping center for the implanted ions.

Transmission electron microscopy study of ion implantation induced Si amorphization

The formation and evolution of radiation damage due to room-temperature Bi implantation in Si at keV and and200 keV was studied during implantation and annealing via in situ transmission electron microscopy (TEM) using the newly developed facility at Orsay. Stereo TEM and a channeling experiment complemented these studies. Our main result is that the hi strained clusters produced in the core of individual cascades are not the nuclei of Si amorphization under Bi bombardment. The overall amorphization is mainly due to the overlap of highly disordered (or amorphous) zones produced outside the cascade core.

Implantation of Bi into GaP. II. channeling studies

Abstract The channeling technique has been used to investigate the properties of Bi-implanted Gap. Measurements of the crystal disorder for 100 keV room temperature implants indicate a damage vs dose curve corresponding to ∼13000 displacements/ion in the linear region and saturation at ∼1.5 × 1013 Bi ions/cm2. Annealing of the radiation damage has been observed and indicates two annealing steps at ∼450°C for light damage and ∼750°C for implants in the 1 × 1014/cm2 range. Difficulties associated with the thermal decomposition of the implanted area have been overcome with the use of SiO x coatings. The experimental details associated with the use of the SiO x layer and with the use of a C12 beam to obtain better depth and mass resolution in the backscattering spectrum are discussed. The lattice location measurements of the Bi impurity show ∼50 per cent of the Bi atoms to be along the 〈110〉 string after a 900°C anneal for a 7.5 × 1013/cm2 implant. In addition, the spectra show ∼25 per cent of the Bi atoms ha...

Substitutional doping during low-dose implantation of Bi and Ti ions in Si at 25°C

Abstract High substitutional components have been observed in Bi and TI implants in silicon without any annealing treatment. Implant conditions were ∼1013 ions/cm2 at 40keV and 25 °C. The lattice location of the implanted atoms has been determined by means of the “channeling” technique.