Effect of Different Deposition Pressure on Diamond Films Deposited by Hot Filament Chemical Vapor Deposition

A hot filament chemical vapor deposition (HFCVD) method was adopted to deposit diamond films at deposition pressures ranging from 2–6 kPa. The effects of deposition pressure on the deposition rate, phase structure, and microstructure of diamond films were investigated. The surface morphology, grain size, micro-structure, and growth rate of the diamond films were analyzed using scanning electron microscopy, X-ray diffraction (XRD), and Raman spectrometry. The experimental results showed that granules on the surface exhibited increasingly compact structure with increasing deposition pressure. The diamond films deposited at various pressures have good compactness, and the particles on the film surfaces are arranged in an ordered manner. All films exhibited orientation along the (111) plane, which was the significant characteristic XRD peak of each diamond film. The (111) peak intensity was the strongest for the film prepared at 2 kPa deposition pressure. Overall, the deposition rate and grain size decreased with increasing deposition pressure, provided other deposition conditions remained unchanged. However, the densification of the microstructure and the nucleation density increased with increasing deposition pressure. Secondary nucleation became more pronounced as deposition pressure increased, and grain size decreased as nucleation density increased.

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Effect of Carbon Concentration on the Optical Properties of Nanocrystalline Diamond Films Deposited by Hot-Filament Chemical Vapor Deposition Method

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2008.18285 ◽

2008 ◽

Vol 8 (5) ◽

pp. 2534-2539

Author(s):

Linjun Wang ◽

Jianmin Liu ◽

Ling Ren ◽

Qingfeng Su ◽

Weimin Shi ◽

...

Keyword(s):

Grain Size ◽

Optical Properties ◽

Chemical Vapor Deposition ◽

Carbon Concentration ◽

Diamond Film ◽

Vapor Deposition ◽

Diamond Films ◽

Chemical Vapor ◽

Diamond Grain ◽

Hot Filament

With reducing diamond grain size to nano-grade, the increase of grain boundaries and non-diamond phase will result in the change of the optical properties of chemical vapor deposition (CVD) diamond films. In this paper, the structure, morphology and optical properties of nanocrystalline diamond (NCD) films, deposited by hot-filament chemical vapor deposition (HFCVD) method under different carbon concentration, are investigated by SEM, Raman scattering spectroscopy, as well as optical transmission spectra and spectroscopic ellipsometry. With increasing the carbon concentration during the film deposition, the diamond grain size is reduced and thus a smooth diamond film can be obtained. According to the data on the absorption coefficient in the wavelength range from 200 to 1100 nm, the optical gap of the NCD films decreases from 4.3 eV to 3.2 eV with increasing the carbon concentration from 2.0% to 3.0%. From the fitting results on the spectroscopic ellipsometric data with a four-layer model in the photon energy range of 0.75–1.5 eV, we can find the diamond film has a lower refractive index (n) and a higher extinction coefficient (k) when the carbon concentration increases.

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Intrinsic stress evolution in diamond films prepared in a CH4H2NH3 hot filament chemical vapor deposition system

Diamond and Related Materials ◽

10.1016/s0925-9635(00)00265-x ◽

2000 ◽

Vol 9 (7) ◽

pp. 1388-1392 ◽

Cited By ~ 14

Author(s):

N.G Shang ◽

C.S Lee ◽

Z.D Lin ◽

I Bello ◽

S.T Lee

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Diamond Films ◽

Chemical Vapor ◽

Intrinsic Stress ◽

Stress Evolution ◽

Hot Filament

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Examination of the material properties and performance of thin-diamond film cutting tool inserts produced by arc-jet and hot filament chemical vapor deposition

Journal of Materials Research ◽

10.1557/jmr.1996.0221 ◽

1996 ◽

Vol 11 (7) ◽

pp. 1765-1775 ◽

Cited By ~ 17

Author(s):

James M. Olson ◽

Michael J. Dawes

Keyword(s):

Wear Resistance ◽

Chemical Vapor Deposition ◽

Diamond Film ◽

Vapor Deposition ◽

Cutting Tool ◽

Diamond Films ◽

Chemical Vapor ◽

Polycrystalline Diamond ◽

And Performance ◽

Hot Filament

Thin diamond film coated WC-Co cutting tool inserts were produced using arc-jet and hot-filament chemical vapor deposition. The diamond films were characterized using SEM, XRD, and Raman spectroscopy to examine crystal structure, fracture mode, thickness, crystalline orientation, diamond quality, and residual stress. The performance of the tools was evaluated by comparing the wear resistance of the materials to brazed polycrystalline diamond-tipped cutting tool inserts (PCD) while machining A390 aluminum (18% silicon). Results from the experiments carried out in this study suggest that the wear resistance of the thin diamond films is primarily related to the grain boundary strength, crystal orientation, and the density of microdefects in the diamond film.

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Quantitative Modelling of Nucleation Kinetics in Experiments for Poly-Si Growth on Sio2 by Hot-Wire Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-664-a1.3 ◽

2001 ◽

Vol 664 ◽

Cited By ~ 1

Author(s):

Maribeth Swiatek ◽

Jason K. Holt ◽

Harry A. Atwater

Keyword(s):

Activation Energy ◽

Grain Size ◽

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Chemical Vapor ◽

Nucleation Density ◽

Hot Wire ◽

Nucleation Kinetics ◽

Temperature Dependent ◽

Cluster Density

ABSTRACTWe apply a rate-equation pair binding model of nucleation kinetics [1] to the nucleation of Si islands grown by hot-wire chemical vapor deposition on SiO2 substrates. Previously, we had demonstrated an increase in grain size of polycrystalline Si films with H2 dilution from 40 nm using 100 mTorr of 1% SiH4 in He to 85 nm with the addition of 20 mTorr H2. [2] This increase in grain size is attributed to atomic H etching of Si monomers rather than stable Si clusters during the early stages of nucleation, decreasing the nucleation density. Atomic force microscopy (AFM) measurements show that the nucleation density increases sublinearly with time at low coverage, implying a fast nucleation rate until a critical density is reached, after which grain growth begins. The nucleation density decreases with increasing H2 dilution (H2:SiH4), which is an effect of the etching mechanism, and with increasing temperature, due to enhanced Si monomer diffusivity on SiO2. From temperature-dependent measurements, we estimate the activation energy for surface diffusion of Si monomers on SiO2 to be 0.47 ± 0.09 eV. Simulations of the temperature-dependent supercritical cluster density lead to an estimated activation energy of 0.42 eV ± 0.01 eV and a surface diffusion coefficient prefactor of 0.1 ± 0.03 cm2/s. H2-dilution-dependent simulations of the supercritical cluster density show an approximately linear relationship between the H2 dilution and the etch rate of clusters.

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Achieving High Nucleation Density of Diamond Film Under Low Pressures in Hot-Filament Chemical Vapor Deposition

MRS Proceedings ◽

10.1557/proc-363-175 ◽

1994 ◽

Vol 363 ◽

Cited By ~ 1

Author(s):

Yan Chen ◽

Jun Mei ◽

Qijin Chen ◽

Zhangda Lin

Keyword(s):

Chemical Vapor Deposition ◽

Diamond Film ◽

Vapor Deposition ◽

Crystalline Silicon ◽

Chemical Vapor ◽

Nucleation Density ◽

Heteroepitaxial Growth ◽

Hot Filament ◽

Low Pressures ◽

Gaseous Source

AbstractDiamond have been deposited rapidly under low pressures (<0.1 Torr) via hot filament chemical vapor deposition (HFCVD) on either scratched or mirror-smooth single crystalline silicon and titanium with nucleation densities of 109–1011/cm2. The nucleation density increases with the pressure decreases. Hydrogen and methane were used as the gaseous source. Raman spectroscopy and scanning electron microscopy(SEM) were used to analyze the obtained films. This result breaks through the limit that diamond film can only be synthesized above 10 Torr, showing a promising prospect that, as is essential for heteroepitaxial growth of monocrystalline diamond films, diamond film can be easily nucleated on unscratched substrate via Hot Filament CVD.

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Nucleation and selected area deposition of diamond by biased hot filament chemical vapor deposition

Journal of Materials Research ◽

10.1557/jmr.1995.0425 ◽

1995 ◽

Vol 10 (2) ◽

pp. 425-430 ◽

Cited By ~ 48

Author(s):

W. Zhu ◽

F.R. Sivazlian ◽

B.R. Stoner ◽

J.T. Glass

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Substrate Surface ◽

Chemical Vapor ◽

Wire Mesh ◽

Reactor Wall ◽

Nucleation Density ◽

Si Substrate ◽

Diamond Nucleation ◽

Hot Filament

This paper describes a process for uniformly enhancing the nucleation density of diamond films on silicon (Si) substrates via dc-biased hot filament chemical vapor deposition (HFCVD). The Si substrate was negatively biased and the tungsten (W) filaments were positively biased relative to the grounded stainless steel reactor wall. It was found that by directly applying such a negative bias to the Si substrate in a typical HFCVD process, the enhanced diamond nucleation occurred only along the edges of the Si wafer. This resulted in an extremely nonuniform nucleation pattern. Several modifications were introduced to the design of the substrate holder, including a metal wire-mesh inserted between the filaments and the substrate, in the aim of making the impinging ion flux more uniformly distributed across the substrate surface. With such improved growth system designs, uniform enhancement of diamond nucleation across the substrate surface was realized. In addition, the use of certain metallic wire mesh sizes during biasing also enabled patterned or selective diamond deposition.

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