Determination of the atomic nitrogen flux from a radio frequency plasma nitride source for molecular beam epitaxy systems

Voulot, D.; McCullough, Robert; Thompson, W. R.; Burns, D. Thorburn; Geddes, J; Cosimini, G. J.; Nelson, Erik; Chow, P. P.; Klaassen, Jody J.

doi:10.1116/1.581498

Cited by 24 publications

(3 citation statements)

References 5 publications

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“…Afterwards, some of the deposited DLC thin films were then subjected to postdeposition nitrogen doping using an atomic nitrogen flux from an RF plasma source exhibiting up to 40% nitrogen dissociation and an atomic fluxes of ϳ0.85 ϫ 10 18 atoms/s. 7 The RF plasma source is an ultrahigh vacuum (UHV) compatible source. The source consists of pyrolytic boron nitride (PBN) cylindrical plasma tube, surrounded by water-cooled RF coil operating at 13.56 MHz.…”

Section: Methodsmentioning

confidence: 99%

Human microvascular endothelial cellular interaction with atomic N‐doped DLC compared with Si‐doped DLC thin films

et al. 2006

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This article reports results of endothelial cell interaction with atom beam source N-doped a-C:H (diamond-like carbon, DLC) as it compares with that of Si-doped DLC thin films. The RF plasma source exhibits up to 40% N-dissociation and N-atomic fluxes of approximately 0.85 x 10(18) atoms/s, which ensures better atomic nitrogen incorporation. Two different types of nitrogen species (with and without the use of sweep plates to remove charged ions) were employed for nitrogen doping. The number of attached endothelial cells is highest on Si-DLC, followed by the N-DLC (where the sweep plates were used to remove ions), the N-DLC (without the use of sweep plates), undoped DLC, and finally the uncoated sample. The contact angle values for these films suggest that water contact angle is higher in the atomic nitrogen neutral films and Si-DLC films compared to the ionized-nitrogen specie doped films and undoped DLC thin films, suggesting that the more hydrophobic films, semiconducting films, and film with relieved stress have better interaction with human microvascular endothelial cells. It seems evident that N-doping increases the Raman I(D)/I(G) ratios, whereas N-neutral doping decreases it slightly and Si-doping decreases it even further. In this study, lower Raman I(D)/I(G) ratios are associated with increased sp(3)/sp(2) ratio, an increased H concentration, photoluminescence intensity, and a higher endothelial cellular adhesion. These investigations could be relevant to biocompatibility assessment of nanostructured biomaterials and tissue engineering.

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Section: Methodsmentioning

confidence: 99%

Human microvascular endothelial cellular interaction with atomic N‐doped DLC compared with Si‐doped DLC thin films

et al. 2006

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“…However, due to high bond energy, it is quite difficult to break the molecular nitrogen to achieve a higher dissociation fraction (DF) [14][15][16]. Although several works have been published on pure nitrogen plasma, produced via various kinds of discharge methods, such as microwave [17][18][19][20][21], radio frequency (RF) [8,9,22] and helicon discharge [7], for all the cases, the reported DF of nitrogen molecules stays at a minimal level in the low power regime (<600 W). Apart from this, it is observed that when nitrogen is mixed with other gases like hydrogen, argon etc, the DF gets a boost and for argon mixing, the stability of the overall plasma remains intact even at higher argon proportions [15,16,[23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Changing pattern of N₂ dissociation in N₂–Ar RF plasma during E–H mode transition

Mukherjee¹,

Chakraborty²,

Sharma³

et al. 2023

Plasma Sources Sci. Technol.

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The behaviour of nitrogen plasma mixed with varying proportions of argon (10%-80%) has been investigated under different RF discharge conditions. It is observed that at a relatively low RF power of 200 W (E-mode) the dissociation fraction (DF) of nitrogen increases with the growing concentration of argon whereas the opposite happens for a higher RF power of 1000 W (H-mode) when the DF rapidly falls from a high value as argon percentage starts moving upwards. This rising trend of DF closely follows the argon metastable fraction (MF) in the E-mode and for H-mode it does not follow until the argon percentage crosses 20% mark. The electron density, temperature and electron energy probability function (EEPF) has been obtained using a RF compensated Langmuir probe and to evaluate the vibrational and rotational temperature, DF, MF etc. a separate optical emission spectroscopy technique is incorporated. At 5×10-3 mbar of working pressure and 10% argon content the EEPF profile reveals that the plasma changes from non-Maxwellian to Maxwellian as the RF power jumps from 200 W to 1000 W, and for a fixed RF power the high energy tail tends to move upwards with the gradual increment of argon. These observations have been re-verified theoretically by considering electron-electron collision frequency and electron bounce frequency as a function of electron temperature. Overall, all the major experimental phenomena in this study have been explained in terms of EEPF profile, electron-electron collision effect, electron and gas temperature, electron density and argon metastable population.

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“…25 By OES, Vaudo et al 26 showed a more direct measurement of the dissociation degree and proposed the estimation of D in nitrogen plasmas based on the atomic to molecular ratios. Based on the combined OES and QMS experiments, McCullogh et al 27,28 found a linear relationship between the intensity of the atomic nitrogen line 746.8 nm and the intensity of 4-2 molecular band (750.4 nm) of the first positive system and the quantity D/(1-D). Also, Cho et al 29…”

Section: Introductionmentioning

confidence: 99%

Effect of N2* and N on GaN nanocolumns grown on Si(111) by molecular beam epitaxy

Debnath

Gandhi

Kesaria

et al. 2016

Journal of Applied Physics

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The self-induced growth of GaN nanocolumns (NCs) on Si x N 1Àx /Si (111) is investigated as a function of the ratio of molecular to atomic nitrogen species generated via plasma assisted molecular beam epitaxy. Relative concentrations of the molecular and atomic species are calculated using optical emission spectroscopy. The growth rate (GR), diameter, and density of NCs are found to vary with the molecular to atomic nitrogen species relative abundance ratio within the plasma cavity. With increasing ratio, the GR and diameter of NCs increase while the density of NCs seems to be decreasing. The morphologies and the coalescence of GaN NCs exhibit a trend for molecular/ atomic ratios up to 11, beyond which they still change but at a lower rate. The detrimental effect of taperedness of the NCs decreases with increasing molecular/atomic ratios. This is possibly because of reduction in radial growth in NCs due to increase in diffusivity of nitrogen species with increasing ratios. V

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Determination of the atomic nitrogen flux from a radio frequency plasma nitride source for molecular beam epitaxy systems

Cited by 24 publications

References 5 publications

Human microvascular endothelial cellular interaction with atomic N‐doped DLC compared with Si‐doped DLC thin films

Human microvascular endothelial cellular interaction with atomic N‐doped DLC compared with Si‐doped DLC thin films

Changing pattern of N₂ dissociation in N₂–Ar RF plasma during E–H mode transition

Effect of N2* and N on GaN nanocolumns grown on Si(111) by molecular beam epitaxy

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Determination of the atomic nitrogen flux from a radio frequency plasma nitride source for molecular beam epitaxy systems

Cited by 24 publications

References 5 publications

Human microvascular endothelial cellular interaction with atomic N‐doped DLC compared with Si‐doped DLC thin films

Human microvascular endothelial cellular interaction with atomic N‐doped DLC compared with Si‐doped DLC thin films

Changing pattern of N2 dissociation in N2–Ar RF plasma during E–H mode transition

Effect of N2* and N on GaN nanocolumns grown on Si(111) by molecular beam epitaxy

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Changing pattern of N₂ dissociation in N₂–Ar RF plasma during E–H mode transition