Gas Phase Chemistry Study During Deposition of a-Si:H and μc-Si:H Films by HWCVD using Quadrupole Mass Spectrometry

MRS Proceedings ◽

10.1557/proc-715-a23.5 ◽

2002 ◽

Vol 715 ◽

Author(s):

Samadhan B. Patil ◽

Alka A. Kumbhar ◽

R. O. Dusane

Keyword(s):

Mass Spectrometry ◽

Gas Phase ◽

Chemical Species ◽

Quadrupole Mass ◽

Film Properties ◽

Quadrupole Mass Spectrometry ◽

Gas Phase Chemistry ◽

Hydrogen Dilution ◽

Phase Chemistry

AbstractAmorphous and microcrystalline silicon films were deposited by HWCVD under different deposition conditions and the gas phase chemistry was studied by in situ Quadrupole Mass Spectrometry. Attempt is made to correlate the properties of the films with the gas phase chemistry during deposition. Interestingly, unlike in PECVD, partial pressure of H2 is higher than any other species during deposition of a-Si:H as well as μc-Si:H. Effect of hydrogen dilution on film properties and on concentration of various chemical species in the gas phase is studied. For low hydrogen dilution [H2]/ [SiH4] from 0 to 1 (where [SiH4] is 10 sccm), all films deposited are amorphous with photoconductivity gain of ∼ 106. During deposition of these amorphous films SiH2 was dominant in gas phase next to [H2]. Interestingly [Si]/[SiH2] ratio increases from 0.4 to 0.5 as dilution increased from 0 to 1, and further to more than 1 for higher hydrogen dilution leading to [Si] dominance. At hydrogen dilution ratio 20, consequently films deposited were microcrystalline.

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Mass Spectrometry and Gas-Phase Chemistry of Anilines

ChemInform ◽

10.1002/chin.200730279 ◽

2007 ◽

Vol 38 (30) ◽

Author(s):

Marcos N. Eberlin ◽

Daniella Vasconcellos Augusti ◽

Rodinei Augusti

Keyword(s):

Mass Spectrometry ◽

Gas Phase ◽

Gas Phase Chemistry ◽

Phase Chemistry

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In Situ Mass Spectrometry for Chemical Identification in SiC Epitaxial Deposition

Materials Science Forum ◽

10.4028/www.scientific.net/msf.556-557.121 ◽

2007 ◽

Vol 556-557 ◽

pp. 121-124

Author(s):

Brian H. Ponczak ◽

James D. Oliver ◽

Soon Cho ◽

Gary W. Rubloff

Keyword(s):

Mass Spectrometry ◽

Mass Spectrometer ◽

Chemical Species ◽

Chemical Identification ◽

Quadrupole Mass ◽

Decomposition Products ◽

Epitaxial Deposition ◽

Chemical Modelling ◽

Insight Into

A quadrupole mass spectrometer unit was utilized to accurately detect the chemical species present inside a SiC CVD reactor growth chamber before, during, and after epitaxial deposition. The in-situ mass spectrometer has been able to confirm the presence of silane (SiH4) and propane (C3H8) decomposition products (eg. Si and CH4) that were predicted from chemical modelling, and give insight into specific reaction kinetics. Additionally, the mass spectrometer has positively detected trace amounts of oxygen, which has helped to identify process weaknesses and possible sources of vacuum leaks.

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Depletion of 15N in the center of L1544: Early transition from atomic to molecular nitrogen?

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833607 ◽

2018 ◽

Vol 615 ◽

pp. L16 ◽

Cited By ~ 4

Author(s):

K. Furuya ◽

Y. Watanabe ◽

T. Sakai ◽

Y. Aikawa ◽

S. Yamamoto

Keyword(s):

Gas Phase ◽

Molecular Nitrogen ◽

Abundance Ratio ◽

Elemental Abundance ◽

Evolutionary Stage ◽

Gas Phase Chemistry ◽

Far Ultraviolet ◽

Phase Chemistry ◽

Grain Surface

We performed sensitive observations of the N15ND+(1–0) and 15NND+(1–0) lines toward the prestellar core L1544 using the IRAM 30 m telescope. The lines are not detected down to 3σ levels in 0.2 km s−1 channels of ~6 mK. The non-detection provides the lower limit of the 14N/15N ratio for N2D+ of ~700–800, which is much higher than the elemental abundance ratio in the local interstellar medium of ~200–300. The result indicates that N2 is depleted in 15N in the central part of L1544, because N2D+ preferentially traces the cold dense gas, and because it is a daughter molecule of N2. In situ chemistry is probably not responsible for the 15N depletion in N2; neither low-temperature gas phase chemistry nor isotope selective photodissociation of N2 explains the 15N depletion; the former prefers transferring 15N to N2, while the latter requires the penetration of interstellar far-ultraviolet (FUV) photons into the core center. The most likely explanation is that 15N is preferentially partitioned into ices compared to 14N via the combination of isotope selective photodissociation of N2 and grain surface chemistry in the parent cloud of L1544 or in the outer regions of L1544, which are not fully shielded from the interstellar FUV radiation. The mechanism is most efficient at the chemical transition from atomic to molecular nitrogen. In other words, our result suggests that the gas in the central part of L1544 has previously gone trough the transition from atomic to molecular nitrogen in the earlier evolutionary stage, and that N2 is currently the primary form of gas-phase nitrogen.

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