Low Temperature CVD of Thin, Amorphous Boron‐Carbon Films for Neutron Detectors

Pedersen, Henrik; Höglund, Carina; Birch, Jens; Jensen, Jens; Henry, Anne

doi:10.1002/cvde.201206980

Cited by 28 publications

(37 citation statements)

References 18 publications

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“…39,40 Fabrication of boron carbide coatings by evaporation methods was demonstrated and film thicknesses up to 20 lm were reported, but the deposited areas were of comparatively small size (several cm 2 ). [41][42][43][44] The present report describes the preparation of B 4 C coatings by DC magnetron sputtering on Si and Al substrates. Further, it discusses the results of thorough structural characterization (by spectral reflectance and profilometry, XRD, Scanning Electron Microscopy (SEM), and X-Ray Reflectometry (XRR)) as well as chemical and isotopic analysis (by X-ray-Photoelectron Spectroscopy (XPS), Secondary-Ion-Mass-Spectrometry (SIMS), and nuclear reaction analysis (NRA)).…”

mentioning

confidence: 99%

Boron carbide coatings for neutron detection probed by x-rays, ions, and neutrons to determine thin film quality

Nowak

Störmer

Becker

et al. 2015

Journal of Applied Physics

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Boron carbide coatings for neutron detection probed by x-rays, ions, and neutrons to determine thin film quality He and the associated tremendous increase of its price, the supply of large neutron detection systems with 3 He becomes unaffordable. Alternative neutron detection concepts, therefore, have been invented based on solid 10 B converters. These concepts require development in thin film deposition technique regarding high adhesion, thickness uniformity and chemical purity of the converter coating on large area substrates. We report on the sputter deposition of highly uniform large-area 10 B 4 C coatings of up to 2 lm thickness with a thickness deviation below 4% using the Helmholtz-Zentrum Geesthacht large area sputtering system. The 10 B 4 C coatings are x-ray amorphous and highly adhesive to the substrate. Material analysis by means of X-ray-Photoelectron Spectroscopy, Secondary-Ion-Mass-Spectrometry, and RutherfordBack-Scattering (RBS) revealed low impurities concentration in the coatings. The isotope composition determined by Secondary-Ion-Mass-Spectrometry, RBS, and inelastic nuclear reaction analysis of the converter coatings evidences almost identical 10 B isotope contents in the sputter target and in the deposited coating. Neutron conversion and detection test measurements with variable irradiation geometry of the converter coating demonstrate an average relative quantum efficiency ranging from 65% to 90% for cold neutrons as compared to a black 3 He-monitor. Thus, these converter coatings contribute to the development of 3 He-free prototype detectors based on neutron grazing incidence. Transferring the developed coating process to an industrial scale sputtering system can make alternative 3 He-free converter elements available for large area neutron detection systems.

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mentioning

confidence: 99%

Boron carbide coatings for neutron detection probed by x-rays, ions, and neutrons to determine thin film quality

Nowak

Störmer

Becker

et al. 2015

Journal of Applied Physics

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“…Films deposited on (100)-oriented Si substrates in H2 and Ar atmospheres respectively, within 700 -1200 °C were characterized and discussed together with the previously published results for TEB (400 -600 °C) [33].…”

Section: Teb and Tmb In Thermal Cvdmentioning

confidence: 91%

“…This type of reaction was reported to occur at 300 °C [35], and at higher temperatures the other ethyl groups could further be eliminated to form BH3 [33]. elimination from C2H4 [61].…”

Section: Gas Phase Cvd Chemistry and Quantum Chemical Calculationsmentioning

confidence: 94%

CVD Chemistry of Organoborons for Boron-Carbon Thin Film Depositions

Imam¹

2017

Linköping Studies in Science and Technology. Dissertations

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“…[16][17][18] The PVD method is a line-of-sight deposition technique and while CVD is not to the same extent. CVD has been demonstrated to deposit well-defined, high quality singlephase boron carbide films [14].…”

Section: Boron Carbidesmentioning

confidence: 99%

“…We used a combined experimental and theoretical approach with both film deposition and quantum chemical calculations. We deposited films in two different atmospheres; H 2 and Ar within 700 -1200 °C and used also previously published results (400-600 °C) [17] to get a more complete picture.…”

Section: Paper I Gas Phase Chemical Vapor Deposition Chemistry Of Trimentioning

confidence: 99%

Chemical vapour deposition of boron-carbon thin films from organoboron precursors

Yimamu¹,

Maiwulidan²

2016

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Boron-carbon (BxC) thin films enriched in 10B are potential neutron converting layers for 10Bbased solid-state neutron detectors given the good neutron absorption cross-section of 10B atoms in the thin film. Chemical Vapour Deposition (CVD) of such films faces the challenge that the maximum temperature tolerated by the aluminium substrate is 660 °C and low temperature CVD routes for BxC films are thus needed. This thesis presents the use of two different organoboron precursors, triethylboron –B(C2H5)3 (TEB) and trimethylboron – B(CH3)3 (TMB) as single-source precursors for CVD of BxC thin films. The CVD behaviour of TEB in thermal CVD has been studied by both BxC thin film deposition and quantum chemical calculations of the gas phase chemistry at the corresponding CVD conditions. The calculations predict that the gas phase reactions are dominated by β-hydride eliminations of C2H4 to yield BH3. In addition, a complementary bimolecular reaction path based on H2-assisted C2H6 elimination to BH3 is also present at lower temperatures in the presence of hydrogen molecules. A temperature window of 600 – 1000 °C for deposition of X-ray amorphous BxC films with 2.5 ≤ x ≤ 4.5 is identified showing good film density (2.40 – 2.65 g/cm3) which is close to the bulk density of crystalline B4C, 2.52 g/cm3 and high hardness (29 – 39 GPa). The impurity level of H is lowered to < 1 at. % within the temperature window. Plasma chemical vapour deposition has been studied using TMB as single-source precursor in Ar plasma for investigating BxC thin film deposition at lower temperature than allowed by thermal CVD and further understanding of thin film deposition process. The effect of plasma power, total pressure, TMB and Ar gas flow on film composition and morphology are investigated. The highest B/C ratio of 1.9 is obtained at highest plasma power of 2400 W and TMB flow of 7 sccm. The H content in the films seems constant at 15±5 at. %. The B-C bond is dominant in the films with small amount of C-C and B-O bonds, which are likely due to the formation of amorphous carbon and surface oxidation, respectively. The film density is determined as 2.16±0.01 g/cm3 and the internal compressive stresses are measured to be <400 MPa

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Low Temperature CVD of Thin, Amorphous Boron‐Carbon Films for Neutron Detectors

Cited by 28 publications

References 18 publications

Boron carbide coatings for neutron detection probed by x-rays, ions, and neutrons to determine thin film quality

Boron carbide coatings for neutron detection probed by x-rays, ions, and neutrons to determine thin film quality

CVD Chemistry of Organoborons for Boron-Carbon Thin Film Depositions

Chemical vapour deposition of boron-carbon thin films from organoboron precursors

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