Mechanism of surface smoothing of diamond by a hydrogen plasma

Rawles, Robin E.; Komarov, S.F.; Gat, R.; Morris, William G.; Hudson, John B.; D'Evelyn, Mark P.

doi:10.1016/s0925-9635(96)00623-1

Cited by 52 publications

(21 citation statements)

References 18 publications

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“…Further H-plasma treatment leads to an additional roughness enhancement by another factor of ten up to 40 nm rms , although only a layer of about 110 nm is removed by the plasma exposure. The discrepancy between our experiments and those reported in [4,5] might well be due to some different experimental conditions, such as plasma density and/or exposure time. On the other hand, our results are corroborated by Lee and Badzian [8], who have studied the morphology of etched substrates and homoepitaxial diamond films in relation to the miscut angles of the substrates.…”

Section: Discussioncontrasting

confidence: 99%

“…Kühnle and Weis have developed a chemomechanical polishing procedure that reduces the roughness of diamond {100} to less than 100 pm rms [3]. Others have used hydrogen-plasma etching to reduce the surface roughness, resulting in large atomically flat terraces [4,5]. On the other hand, etching of the diamond(100) with atomic hydrogen at an elevated substrate temperature has led to {111} faceting of the surface, which has been interpreted as anisotropic etching of the diamond by the thermal hydrogen atoms [14].…”

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confidence: 99%

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Roughness transitions of diamond(100) induced by hydrogen-plasma treatment

Koslowski

Strobel

Wenig

et al. 1998

Applied Physics A: Materials Science & Processing

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To investigate the influence of hydrogen-plasma treatment on diamond(100) surfaces, heavily boron (B)-doped HPHT diamond crystals were mechanically and chemo-mechanically polished, and exposed to a microwaveassisted hydrogen plasma on a time scale of several minutes. The resulting surface morphology was analyzed on macroscopic scales by stylus profilometry (PFM) and on microscopic scales by STM and AFM. The polished samples have a roughness of typically 100 pm rms (PFM), with no obvious anisotropic structures at the surface. After exposure of the B-doped diamond(100) to the H-plasma, the roughness increases dramatically, and pronounced anisotropic structures appear, these being closely aligned with the crystallographic axis' and planes. An exposure for 3 minutes to the plasma leads to an increase of the roughness to 2-4 nm rms (STM), and a 'brick-wall' pattern appears, formed by weak cusps running along 110 . Very frequently, the cusps are replaced by 'negative' pyramids that are bordered by {11X} facets. After an exposure of an additional 5 minutes, the surface roughness of the B-doped samples increases further to 20-40 nm rms (STM), and frequently exhibits a regular pattern with structures at a characteristic length scale of about 100 nm. Those structures are aligned approximately with 110 and they are faceted with faces of approximately {XX1}. These results will be discussed in terms of strain relaxation, similar to the surface roughening observed on SiGe/Si and anisotropic etching.Many studies have been undertaken on CVD diamond films, towards applications that utilize the outstanding properties of diamond. So far, unmet demands are being put on the quality of those films, especially if one is aiming at utilizing the diamond films for semiconductor applications. Homoepitaxially grown single-crystalline diamond films are closest to meeting such requirements. Even though, nowadays, many research groups are able to grow high-quality diamond films homoepitaxially, various questions related to, for example, the nucleation and growth mechanism, the role of hydrogen in the bulk and at the surface, and the evolution of the morphology upon growth and etching of the diamond remain unanswered.The surface morphology of diamond substrates and films has been investigated by several groups. Since the substrate morphology is at least partly transferred to the film (see, e.g., [1]) and, for example, the resulting step density of a homoepitaxially grown film might influence its electronic properties at the surface [2], an optimized substrate preparation is required. Kühnle and Weis have developed a chemomechanical polishing procedure that reduces the roughness of diamond {100} to less than 100 pm rms [3]. Others have used hydrogen-plasma etching to reduce the surface roughness, resulting in large atomically flat terraces [4,5]. On the other hand, etching of the diamond(100) with atomic hydrogen at an elevated substrate temperature has led to {111} faceting of the surface, which has been interpreted as anisotropic etching of th...

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Section: Discussioncontrasting

confidence: 99%

mentioning

confidence: 99%

Roughness transitions of diamond(100) induced by hydrogen-plasma treatment

Koslowski

Strobel

Wenig

et al. 1998

Applied Physics A: Materials Science & Processing

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“…The roughness of DLC films has been shown to depend on the various deposition methods 163,164 and deposition parameters such as ion energy, [165][166][167][168][169][170] gas mixture 163 and bias voltage. 169 Coating roughness is also dependent on substrate material [171][172][173] and the underlying substrate roughness.…”

Section: Dlc Reviewmentioning

confidence: 99%

“…Increasing the substrate temperature during deposition results in a higher proportion of sp 2 bonding, creating a more graphitic and therefore rougher surface. 165,174,175 Conversely, at temperatures between 700°C and 900°C, film smoothing occurred as an increase in surface diffusion rate accompanied the presence of atomic hydrogen. 176 The effect that film thickness has on film roughness has also been studied.…”

Section: Dlc Reviewmentioning

confidence: 99%

Diamond like carbon coatings for tribology: production techniques, characterisation methods and applications

Hainsworth¹,

Uhure²

2007

International Materials Reviews

180

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There are numerous types of surface coatings available to engineers in order to improve the friction and wear resistance of components. In order to successfully use these coatings in practice, it is important to understand the different types of coatings available, and the factors that control their mechanical and tribological properties. This paper will focus on the application of diamond-like carbon (DLC) coatings in tribological applications. Thus far, DLC coatings have found broad industrial application, particularly in optical and electronic areas. In tribological applications, DLC coatings are now being used successfully as coatings for ball bearings where they decrease the friction coefficient between the ball and race, in shaving applications where they increase the life of razor blades in wet shaving applications, and increasingly in automotive applications such as racing engines and standard production vehicles.The structure and mechanical properties of DLC coatings are dependent on the deposition method and the incorporation of additional elements such as nitrogen, hydrogen, silicon and metal dopants. These additional elements control the hardness of the resultant film, the level of residual stress and the tribological properties. As diamond-like carbon films increasingly become adopted for use in industry, it is important to review the factors that control their 2 of 42 DLC Reviewproperties, and thus, the ultimate performance of these coated components in practical tribological applications.

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“…Indeed, studies using pure H 2 gas but under otherwise similar conditions to those used for diamond CVD show that the etch rate of (100) diamond is <10 nm h −1 . 9 However, this value is somewhat misleading as the etching occurs at defects, usually dislocations on the surface, which etch back laterally to form shallow rectangular etch pits. [10][11][12] Indeed, counting etch pits is often used as a method to determine the number density and distribution of dislocations at a diamond surface.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional kinetic Monte Carlo simulations of diamond chemical vapor deposition

Rodgers

May

Allan

et al. 2015

The Journal of Chemical Physics

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A three-dimensional kinetic Monte Carlo model has been developed to simulate the chemical vapor deposition of a diamond (100) surface under conditions used to grow single-crystal diamond (SCD), microcrystalline diamond (MCD), nanocrystalline diamond (NCD), and ultrananocrystalline diamond (UNCD) films. The model includes adsorption of CH x (x = 0, 3) species, insertion of CH y ( y = 0-2) into surface dimer bonds, etching/desorption of both transient adsorbed species and lattice sidewalls, lattice incorporation, and surface migration but not defect formation or renucleation processes. A value of ∼200 kJ mol −1 for the activation Gibbs energy, ∆G ‡ etch , for etching an adsorbed CH x species reproduces the experimental growth rate accurately. SCD and MCD growths are dominated by migration and step-edge growth, whereas in NCD and UNCD growths, migration is less and species nucleate where they land. Etching of species from the lattice sidewalls has been modelled as a function of geometry and the number of bonded neighbors of each species. Choice of appropriate parameters for the relative decrease in etch rate as a function of number of neighbors allows flat-bottomed etch pits and/or sharp-pointed etch pits to be simulated, which resemble those seen when etching diamond in H 2 or O 2 atmospheres. Simulation of surface defects using unetchable, immobile species reproduces other observed growth phenomena, such as needles and hillocks. The critical nucleus for new layer growth is 2 adjacent surface carbons, irrespective of the growth regime. We conclude that twinning and formation of multiple grains rather than pristine single-crystals may be a result of misoriented growth islands merging, with each island forming a grain, rather than renucleation caused by an adsorbing defect species. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

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Mechanism of surface smoothing of diamond by a hydrogen plasma

Cited by 52 publications

References 18 publications

Roughness transitions of diamond(100) induced by hydrogen-plasma treatment

Roughness transitions of diamond(100) induced by hydrogen-plasma treatment

Diamond like carbon coatings for tribology: production techniques, characterisation methods and applications

Three-dimensional kinetic Monte Carlo simulations of diamond chemical vapor deposition

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