Effect of oxygen and nitrogen concentration of nitrogen doped TiOx film as photocatalyst prepared by reactive sputtering

ABSTRACTAn effect of the nitrogen concentration on the concentrations of deep-level defects in bulk 6H-SiC single crystals is investigated. Six electron traps labeled as T1A, T1B, T2, T3, T4 and T5 with activation energies of 0.34, 0.40, 0.64, 0.67, 0.69, and 1.53 eV, respectively, were revealed. The traps T1A (0.34 eV) and T1B (0.40 eV), observed in the samples with the nitrogen concentration ranging from ∼2×1017 to 5×1017 cm−3, are attributed to complexes formed by carbon vacancies located at various lattice sites and carbon antisites. The concentrations of traps T2 (0.64 eV) and T3 (0.67 eV) have been found to rise from ∼5×1015 to ∼1×1017 cm−3 with increasing the nitrogen concentration from ∼2×1017 to ∼2.0×1018 cm−3. These traps are assigned to complexes involving silicon vacancies occupying hexagonal and quasi-cubic sites, respectively, and nitrogen atoms. The trap T4 (0.69 eV) concentration also substantially rises with increasing the nitrogen concentration and it is likely to be related to complexes formed by carbon antisites and nitrogen atoms. The midgap trap T5 (1.53 eV) is presumably associated with vanadium contamination. The presented results show that doping with nitrogen involves a significant change in the defect structure of 6H-SiC single crystals.

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Thickness-Dependant Electrical Characteristics of Nitrogen-Doped Polycrystalline 3C-SiC Thin Films Deposited by LPCVD

MRS Proceedings ◽

10.1557/proc-1222-dd02-33 ◽

2009 ◽

Vol 1222 ◽

Cited By ~ 1

Author(s):

Man I Lei ◽

Te-Hao Lee ◽

Mehran Mehregany

Keyword(s):

Thin Films ◽

Electrical Resistivity ◽

Film Thickness ◽

Secondary Ion Mass Spectrometry ◽

Boundary Effect ◽

Nitrogen Concentration ◽

Nitrogen Doped ◽

Initial Stage ◽

Columnar Grains ◽

Secondary Ion

AbstractThe effect of film thickness on the electrical resistivity of heavily-nitrogen-doped polycrystalline SiC (poly-SiC) thin films is investigated. The resistivity of poly-SiC thin films decreases by a factor of ˜7 for thickness increasing from 100 nm-thick to 1.78 μm-thick; the resistivity begins to stabilize as thickness approaches 1 μm. The increased resistivity for the thinner films is shown to be related to the grain boundary effect. Secondary ion mass spectrometry indicates a nitrogen concentration of 9×1020 atoms/cm3 in the films. However, Hall measurements reveal that only 45% of the dopants are electrically active in the 100 nm-thick film. The percentage of active dopants rises to 80% when film thickness increases to 680 nm. From the studies of surface roughness and microstructure, it is seen that small grains are formed at the initial stage of deposition, which then grow into larger columnar grains as film thickness increases. The presence of a large density of grain boundaries and limited grain growth for the very thin films contribute to increased electrical resistivity from increased trapped mobile carriers and reduced carrier mobility. The free carrier trapping phenomenon can further be observed in the temperature-dependence of resistance measurement.

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Dopamine-derived nitrogen-doped carboxyl multiwalled carbon nanotube-modified graphite felt with improved electrochemical activity for vanadium redox flow batteries

Royal Society Open Science ◽

10.1098/rsos.200402 ◽

2020 ◽

Vol 7 (7) ◽

pp. 200402

Author(s):

Qiang Li ◽

Anyu Bai ◽

Tianyu Zhang ◽

Song Li ◽

Hong Sun

Keyword(s):

Carbon Nanotubes ◽

Multiwalled Carbon Nanotubes ◽

Synergetic Effect ◽

Electrochemical Activity ◽

Vanadium Redox Flow Battery ◽

Multiwalled Carbon ◽

Graphite Felt ◽

Nitrogen Doped ◽

Effect Of Oxygen ◽

Vanadium Redox

Improving the electrochemical activity of electrodes is essential to the development of vanadium redox flow battery (VRFB). In this work, we prepared a novel electrode with the modification of nitrogen-doped carboxyl multiwalled carbon nanotubes using dopamine as an eco-friendly nitrogen source (carboxyl MWCNT@PDAt). Characterization and electrochemical measurements reveal that the synthesized carboxyl MWCNT@PDAt-modified graphite felt electrode (carboxyl MWCNT@PDAt/GF) exhibits excellent electrochemical performance toward VO 2+ / V O 2 + reaction. Superior battery performance was obtained with the energy efficiency of 80.54% at a current density of 80 mA cm −2 . Excellent durability of the carboxyl MWCNT@PDAt/GF electrode was confirmed by long-term charge/discharge tests. The enhanced reaction kinetics of VO 2+ / V O 2 + is ascribed to the synergetic effect of oxygen and nitrogen containing groups on graphite felt surface and the presence of nitrogen-doped carboxyl multiwalled carbon nanotubes (MWCNT). The facile approach proposed in this paper provides a new route to the fabrication of electrode with excellent performance for VRFB.

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Calibration of IR Absorbance in Highly Nitrogen Doped Silicon

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.205-206.234 ◽

2013 ◽

Vol 205-206 ◽

pp. 234-237

Author(s):

Kevin Lauer ◽

Christian Möller ◽

Rudolf Porytskyy ◽

Hartmuth Strutzberg ◽

Dirk Schulze ◽

...

Keyword(s):

Absorption Coefficient ◽

Infrared Absorption ◽

Nitrogen Concentration ◽

Calibration Factor ◽

Ir Absorption ◽

Calibration Function ◽

Nitrogen Doped ◽

Float Zone ◽

Doped Silicon ◽

Infrared Absorption Spectra

Infrared absorption spectra of highly nitrogen doped multicrystalline float zone silicon are reported. By measuring the nitrogen content in silicon using SIMS, a calibration function of the IR absorption coefficient at 963 cm-1(T = 300 K) and the nitrogen concentration is deduced:cN= (1.29 ± 0.05)×1017cm2α963. The calibration factor is 30 % less than the calibration factor reported by Y. Itoh et al. [Appl. Phys. Lett. 47 (1985) 488].

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Nitrogen segregation in nanocarbons

Faraday Discussions ◽

10.1039/c4fd00111g ◽

2014 ◽

Vol 173 ◽

pp. 215-232 ◽

Cited By ~ 10

Author(s):

C. P. Ewels ◽

D. Erbahar ◽

Ph. Wagner ◽

X. Rocquefelte ◽

R. Arenal ◽

...

Keyword(s):

Density Functional ◽

Nitrogen Doping ◽

Carbon Nanomaterials ◽

Nitrogen Concentration ◽

Critical Threshold ◽

Nitrogen Doped ◽

Low Concentrations ◽

Polycyclic Aromatic ◽

Nitrogen Doped Carbon ◽

Electron Energy Loss

We explore the behaviour of nitrogen doping in carbon nanomaterials, notably graphene, nanotubes, and carbon thin films. This is initially via a brief review of the literature, followed by a series of atomistic density functional calculations. We show that at low concentrations, substitutional nitrogen doping in the sp2-C graphenic basal plane is favoured, however once the nitrogen concentration reaches a critical threshold there is a transition towards the formation of the more thermodynamically-favoured nitrogen terminated ‘zigzag’ type edges. These can occur either via formation of finite patches (polycyclic aromatic azacarbons), strips of sp2 carbon with zigzag nitrogen edges, or internal nitrogen-terminated hole edges within graphenic planes. This transition to edge formation is especially favoured when the nitrogen can be partially functionalised with, e.g. hydrogen. By comparison with available literature results, notably from electron energy loss spectroscopy and X-ray spectroscopy, the current results suggest that much of the nitrogen believed to be incorporated into carbon nanoobjects is instead likely to be present terminating the edges of carbonaceous impurities attached to nanoobject's surface. By comparison to nitrogen-doped tetrahedrally amorphous carbon, we suggest that this transition at around 10–20% nitrogen concentration and above towards sp2 coordination via internal nitrogen-terminated edge formation may be a general property of nitrogen-doped carbon materials.

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