Oxygen Effect on the Stability of PECVD Boron-Carbon Films

Rybakov, S. Yu.; Шарапов, В. Н.; Gavrilov, L.E.

doi:10.1051/jphyscol:19955109

Cited by 6 publications

(12 citation statements)

References 4 publications

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“… 60 , 62 This assignment of atomic B (non-nitrogen bonded) is also corroborated by the lack of a concurrently emerging N1s component upon cooling, as well as by the disappearance of the 188.1 eV signal upon subsequent air exposure, since atomic boron is known to quickly oxidize in ambient air and desorb as highly volatile boron oxides. 63 The emergence of atomic B on the catalyst surface upon cooling strongly implies B precipitation from the catalyst bulk and in turn suggests dissolution of B in the polycrystalline Cu subsurface/bulk during the high-temperature borazine exposure.…”

Section: Resultsmentioning

confidence: 99%

“…Returning to the XPS data in Figure 3 b,c, we find that after extended air exposure the N1s spectra show an additional small component at ∼400.5 eV that does not have a B1s counterpart and is attributed to the formation of N–O bonds. 63 , 67 Further details on the effect of oxygen exposure of samples is provided below. We note that the final in situ XPS fingerprint after air exposure (step 7) in Figure 3 b,c resembles our X-ray photoelectron spectra of the ex situ grown few-layer h-BN in Figure 2 e,f which highlights the validity and relevance of our in situ measurements for scalable high-quality h-BN growth under realistic process conditions.…”

Section: Resultsmentioning

confidence: 99%

“…This points toward oxygen-mediated disintegration of the h-BN film on the Cu foil upon vacuum annealing, where the oxygen was fed from the Cu oxide underneath the h-BN. The formed boron oxides are largely volatile 63 resulting in loss of B and N into the gas phase. This is in stark contrast to the higher stability of the “fresh” h-BN islands in Figure 6 which under similar treatment only showed signs of minor degradation.…”

Section: Resultsmentioning

confidence: 99%

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In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper

et al. 2014

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Using a combination of complementary in situ X-ray photoelectron spectroscopy and X-ray diffraction, we study the fundamental mechanisms underlying the chemical vapor deposition (CVD) of hexagonal boron nitride (h-BN) on polycrystalline Cu. The nucleation and growth of h-BN layers is found to occur isothermally, i.e., at constant elevated temperature, on the Cu surface during exposure to borazine. A Cu lattice expansion during borazine exposure and B precipitation from Cu upon cooling highlight that B is incorporated into the Cu bulk, i.e., that growth is not just surface-mediated. On this basis we suggest that B is taken up in the Cu catalyst while N is not (by relative amounts), indicating element-specific feeding mechanisms including the bulk of the catalyst. We further show that oxygen intercalation readily occurs under as-grown h-BN during ambient air exposure, as is common in further processing, and that this negatively affects the stability of h-BN on the catalyst. For extended air exposure Cu oxidation is observed, and upon re-heating in vacuum an oxygen-mediated disintegration of the h-BN film via volatile boron oxides occurs. Importantly, this disintegration is catalyst mediated, i.e., occurs at the catalyst/h-BN interface and depends on the level of oxygen fed to this interface. In turn, however, deliberate feeding of oxygen during h-BN deposition can positively affect control over film morphology. We discuss the implications of these observations in the context of corrosion protection and relate them to challenges in process integration and heterostructure CVD.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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In Situ Observations during Chemical Vapor Deposition of Hexagonal Boron Nitride on Polycrystalline Copper

et al. 2014

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“…It is known that boron carbide reacts with O 2 at high temperatures (i.e., above 450 • C) to form B 2 O 3 and CO 2 , which can react subsequently with H 2 O to form gaseous boric acids, HBO 2 and H 3 BO 3 [80]. Boron carbide films grown by PECVD are known to react with oxygen to form boron oxides during film deposition, even in the presence of very low quantities of oxygen and at low temperatures (i.e., room temperature to 150 • C), likely due to the reactive ionic species (e.g., O + [81]) present in the plasma [82,83].…”

Section: Materials Characterizationmentioning

confidence: 99%

The local physical structure of amorphous hydrogenated boron carbide: insights from magic angle spinning solid-state NMR spectroscopy

Paquette

Driver

et al. 2011

J. Phys.: Condens. Matter

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Magic angle spinning solid-state nuclear magnetic resonance spectroscopy techniques are applied to the elucidation of the local physical structure of an intermediate product in the plasma-enhanced chemical vapour deposition of thin-film amorphous hydrogenated boron carbide (B(x)C:H(y)) from an orthocarborane precursor. Experimental chemical shifts are compared with theoretical shift predictions from ab initio calculations of model molecular compounds to assign atomic chemical environments, while Lee-Goldburg cross-polarization and heteronuclear recoupling experiments are used to confirm atomic connectivities. A model for the B(x)C:H(y) intermediate is proposed wherein the solid is dominated by predominantly hydrogenated carborane icosahedra that are lightly cross-linked via nonhydrogenated intraicosahedral B atoms, either directly through B-B bonds or through extraicosahedral hydrocarbon chains. While there is no clear evidence for extraicosahedral B aside from boron oxides, ∼40% of the C is found to exist as extraicosahedral hydrocarbon species that are intimately bound within the icosahedral network rather than in segregated phases.

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“…Boron-containing polymers were historically commercialized primarily for their chemical and thermomechanical resistance (e.g., Olin's DEXSIL and Union Carbide's UCARSIL). , In addition, boron-containing polymers have been used to immobilize catalysts, as sensor materials, separation media, and optical materials . For instance, because of their remarkable stability, the icosohedral carboranes have been chiefly viewed as ideal candidates for the chemical/thermal strengthening of polymers. ,, However, recently, there has been a growing interest in incorporating these boron clusters into tailored macromolecular structures by means of living or quasi-living polymerizations. − This recrudescence stems from the rising awareness that carborane-based macromolecules can span a gamut of applications, for example, nonlinear optical materials, − precursors for ceramics, − boron neutron capture therapy of cancer (BNCT), , etc.…”

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confidence: 99%