Catalytic decomposition of NH3 on heated Ru and W surfaces

Umemoto, Hironobu; Kashiwagi, Yuta; Ohdaira, Keisuke; Kobayashi, Hiroyuki; Yasui, Kanji

doi:10.1016/j.tsf.2011.01.289

Cited by 6 publications

(8 citation statements)

References 12 publications

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“…This nonlinear dependence is similar to that observed in the catalytic production of NH from NH 3 30,36) and suggests the multistep production of PH. This point will be discussed in §4.1.…”

Section: Lif Measurements Of Ph Radicalssupporting

confidence: 78%

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Catalytic Decomposition of PH₃ on Heated Tungsten Wire Surfaces

Umemoto

Nishihara

Ishikawa

et al. 2012

Jpn. J. Appl. Phys.

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The catalytic decomposition processes of PH 3 on heated tungsten surfaces were studied to clarify the mechanisms governing phosphorus doping into silicon substrates. Mass spectrometric measurements show that PH 3 can be decomposed by more than 50% over 2000 K. H, P, PH, and PH 2 radicals were identified by laser spectroscopic techniques. Absolute density measurements of these radical species, as well as their PH 3 flow rate dependence, show that the major products on the catalyst surfaces are P and H atoms, while PH and PH 2 are produced in secondary processes in the gas phase. In other words, catalytic decomposition, unlike plasma decomposition processes, can be a clean source of P atoms, which can be the only major dopant precursors. In the presence of an excess amount of H 2 , the apparent decomposition efficiency is small. This can be explained by rapid cyclic reactions including decomposition, deposition, and etching to reproduce PH 3 .

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Section: Lif Measurements Of Ph Radicalssupporting

confidence: 78%

“…In the catalytic decomposition of NH 3 , we have assumed a process to produce NH from adsorbed NH 2 and H on catalyst surfaces. 36) Similar processes, such as PH 2 +H→PH+H 2 and PH+H→P+H 2 may also take place on the catalyst surfaces.…”

Section: Reaction Kineticsmentioning

confidence: 99%

Catalytic Decomposition of PH₃ on Heated Tungsten Wire Surfaces

Umemoto

Nishihara

Ishikawa

et al. 2012

Jpn. J. Appl. Phys.

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“…The absolute density was estimated by comparing the LIF intensity under saturated conditions with the intensity of Rayleigh scattering caused by Ar. This procedure was similar to those employed for the absolute density measurements of other radical species, such as Si atoms. ,,,, The differential cross section for Rayleigh scattering by Ar was calculated to be 1.31 × 10 –26 cm 2 from the wavelength, 249.8 nm, and the refractive index, 1.00031. Under saturated conditions, the population ratio of the upper 2s 2 3s 2 S 1/2 state to that of the lower 2s 2 2p 2 P 3/2 state is 1/4 when the excitation laser is linearly polarized .…”

Section: Experimental Methodsmentioning

confidence: 99%

Production of B Atoms and BH Radicals from B₂H₆/He/H₂ Mixtures Activated on Heated W Wires

Umemoto

Kanemitsu

Tanaka³

2014

J. Phys. Chem. A

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B atoms and BH radicals could be identified by laser-induced fluorescence when B2H6/He/H2 mixtures were activated on heated tungsten wires. The densities of these radical species increased not only with the wire temperature but also with the partial pressure of H2. The densities in the presence of 0.026 Pa of B2H6 and 2.6 Pa of H2 were on the order of 10(11) cm(-3) both for B and BH when the wire temperature was 2000 K. Densities in the absence of a H2 flow were much smaller, suggesting that the direct production of these species on wire surfaces is minor. B and BH must be produced in the H atom shifting reactions, BH(x) + H → BH(x-1) + H2 (x = 1-3), in the gas phase, while H atoms are produced from H2 on wire surfaces. The B atom density increased monotonously with the H atom density, while the BH density showed saturation. These tendencies could be reproduced by simple modeling based on ab initio potential energy calculations and the transition-state theoretical calculations of the rate constants. The absolute densities could also be reproduced within a factor of 2.5.

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“…D 2 desorption was observed only from the monodeuteride species at 780 K. No PL was observed when the NCs were subjected to dissociative (thermal) adsorption of ND 3 because, as reported herein, thermal adsorption did not generate enough ND 2 and D to saturate the dangling bonds and relax the Si−Si bonds. Umemoto et al have shown that ammonia decomposition on a hot tungsten filament results in the formation of predominantly H atoms and NH 2 radicals, with NH radicals formed as a minor product . In separate experiments, a hot tungsten filament was used to predissociate ND 3 before adsorption on the NC surface .…”

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confidence: 99%

“…XPS indicates that predominantly Si-ND 2 species are adsorbed on the NC surface at these low ND 3 doses. The dissociation of NH 3 (ND 3 ) over a hot filament results in the formation of predominantly H (D) atoms and NH 2 (ND 2 ) radicals . These radicals initially passivate the dangling bonds on the NC surface at low doses, leaving the reconstructed surface dimers and steps intact.…”

mentioning

confidence: 99%

Effect of Surface Chemistry on Quantum Confinement and Photoluminescence of Ammonia-Passivated Silicon Nanocrystals

Salivati

Shuall²,

McCrate

et al. 2010

J. Phys. Chem. Lett.

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Silicon (Si) nanocrystals (NCs) less than 5 nm in diameter are grown on SiO 2 surfaces using hot wire chemical vapor deposition, and the dangling bonds and the reconstructed bonds at the NC surface are passivated and transformed with D and ND x by using deuterated ammonia (ND 3 ), which is predissociated over a hot filament. At low hot wire ND 3 doses, photoluminescence (PL) emission is observed from a defect state at 1000 nm corresponding to reconstructed surface bonds capped by predominantly monodeuteride and Si-ND 2 species. As the hot wire ND 3 dose is increased, di-and trideuteride species form, and intense PL is observed around 800 nm, which does not shift with NC size and is associated with defect levels resulting from ND x insertion into the strained Si-Si bonds forming Si 2 dND. A clean bandgap can be realized with fully relaxed and fully terminated NC surfaces consisting of di-and trideuterides and SiND 2 . SECTION Nanoparticles and Nanostructures

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Catalytic decomposition of NH3 on heated Ru and W surfaces

Cited by 6 publications

References 12 publications

Catalytic Decomposition of PH₃ on Heated Tungsten Wire Surfaces

Catalytic Decomposition of PH₃ on Heated Tungsten Wire Surfaces

Production of B Atoms and BH Radicals from B₂H₆/He/H₂ Mixtures Activated on Heated W Wires

Effect of Surface Chemistry on Quantum Confinement and Photoluminescence of Ammonia-Passivated Silicon Nanocrystals

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Catalytic decomposition of NH3 on heated Ru and W surfaces

Cited by 6 publications

References 12 publications

Catalytic Decomposition of PH3 on Heated Tungsten Wire Surfaces

Catalytic Decomposition of PH3 on Heated Tungsten Wire Surfaces

Production of B Atoms and BH Radicals from B2H6/He/H2 Mixtures Activated on Heated W Wires

Effect of Surface Chemistry on Quantum Confinement and Photoluminescence of Ammonia-Passivated Silicon Nanocrystals

Contact Info

Product

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Catalytic Decomposition of PH₃ on Heated Tungsten Wire Surfaces

Catalytic Decomposition of PH₃ on Heated Tungsten Wire Surfaces

Production of B Atoms and BH Radicals from B₂H₆/He/H₂ Mixtures Activated on Heated W Wires