Pulsed laser deposition of diamondlike carbon films on polycarbonate

Bonelli, M.; Miotello, A.; Mosaner, Paolo; Casiraghi, Cinzia; Ossi, P.M.

doi:10.1063/1.1530725

Cited by 38 publications

(11 citation statements)

References 29 publications

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“…This result does not contradict either our own earlier investigations [15] or work by other authors on laser vacuum deposition [16,17]. Taking into account this thickness and also based on the spectral transparency of the film (Fig.…”

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confidence: 45%

Determination of the optical bandgap for diamond-like carbon films obtained by laser plasma deposition

et al. 2007

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We have obtained and analyzed the optical transmission spectra of diamond-like carbon films deposited on quartz substrates by pulsed laser deposition (λ = 1064 nm, τ = 20 nsec, q = 4.9⋅10 8 W/cm 2 ) under vacuum . Based on the spectra obtained, we have estimated the size of the bandgap by the Tauc method, and also have studied the growth dynamics of the coatings formed.Introduction. Due to the increasing interest in diamond electronics, diamond-like carbon films have been the subject of intensive study for several decades. Using diamond-like carbon nanostructures instead of the silicon type can result in creation of chips with a higher concentration of transistors, since diamond has high thermal conductivity and heat resistance (sublimation temperature above 3000 K [1]). In addition, diamond-like carbon films are chemically inert and extremely strong.Recently, increasing attention has been focused on synthesis and study of diamond-like carbon films of different structures (amorphous, crystalline, having different ratios of sp 2 and sp 3 carbon bonds, etc.) [2, 3] and different compositions (containing hydrogen, nitrogen, and other elements) [4]. Efficient methods have been found for doping diamond-like carbon films with boron to obtain p-type conductivity in them [5].Laser spraying of carbon films provides greater opportunities for obtaining new materials with unusual properties. In deposition of these materials, a large role is played by the stored energy of the particles of the carbon plasma, under the action of which new, promising structural forms are obtained (tetrahedral carbon, nanocrystalline carbon, etc.). The laser method has an advantage over other methods for depositing thin films, since when coatings are deposited by this method, it is easier to monitor the production conditions for obtaining the deposited coating. Furthermore, laser radiation itself is "sterile" [6].Vacuum deposition of films is the most widely used and universal method for obtaining thin-film structures for broadest application (including complicated applications) in production of active film semiconductor structures (p-n junctions) [7].The main problem during deposition is to obtain films having properties which most fully correspond to their area of application. Very often we need to obtain films with high optical transparency, and in addition we can determine other parameters of the film from the spectral characteristics.The aim of this work was to determine the optical bandgap and also to study the effect of the deposition parameters on the optical properties of diamond-like carbon films.The Experiment. The schematic diagram for the experimental system is shown in Fig. 1. For deposition of diamond-like carbon films, we used an LS-2137 YAG:Nd 3+ laser (Lotis TII) with repetition frequency 5 Hz for the laser pulses, wavelength λ = 1064 nm, and pulse length τ = 20 nsec. The laser pulse energy was detected using an IMO-3 power meter. To do this, some of the laser radiation was diverted to the measurement head by means of a 10% beam...

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confidence: 45%

Determination of the optical bandgap for diamond-like carbon films obtained by laser plasma deposition

et al. 2007

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“…These features complicate the interpretation of improved fatigue properties. Table 1 lists a summary [16,34,80,[106][107][108][109][110][111] of some processing-associated properties for the fabrication methods discussed in the previous section.…”

Section: Severe Plastic Deformation Processingmentioning

confidence: 99%

A Review of Fatigue Behavior in Nanocrystalline Metals

2009

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Nanocrystalline metals have been shown to exhibit unique mechanical behavior, including break-down in Hall-Petch behavior, suppression of dislocation-mediated plasticity, induction of grain boundary sliding, and induction of mechanical grain coarsening. Early research on the fatigue behavior of nanocrystalline metals shows evidence of improved fatigue resistance compared to traditional microcrystalline metals. In this review, experimental and modeling observations are used to evaluate aspects of cyclic plasticity, microstructural stability, crack initiation processes, and crack propagation processes. In cyclic plasticity studies to date, nanocrystalline metals have exhibited strongly rate-dependent cyclic hardening, suggesting the importance of diffusive deformation mechanisms such as grain-boundary sliding. The cyclic deformation processes have also been shown to cause substantial mechanicallyinduced grain coarsening reminiscent of coarsening observed during large-strain monotonic deformation of nanocrystalline metals. The crack-initiation process in nanocrystalline metals has been associated with both subsurface internal defects and surface extrusions, although it is unclear how these extrusions form when the grain size is below the scale necessary for persistent slip band formation. Finally, as expected, nanocrystalline metals have very little resistance to crack propagation due to limited plasticity and the lack of crack path tortuosity among other factors. Nevertheless, like bulk metallic glasses, nanocrystalline metals exhibit both ductile fatigue striations and metal-like Paris-law behavior. The review provides both a comprehensive critical survey of existing literature and a summary of key areas for further investigation.

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“…According to the Raman spectrum analysis [5] the range of values of both I D /I G and G maximum indicate that the fraction of sp 3 -co-ordinated carbon in these CA films does not exceed 10%. The presence of DLC in the films is excluded because the range of power density values adopted would result in ta-C formation when PLD is performed in vacuum [2], while it would correspond to values of the I D /I G ratio between 1 and 1.2 for films deposited in a buffer gas [6]. Raman spectra also give no indication of the fullerene formation, due to the lack of any vibrational feature attributed to C 60 [7].…”

Section: Resultsmentioning

confidence: 98%