Rare-earth modified amorphous carbon films: Effects of erbium and gadolinium on the structural evolution and mechanical properties

Tillmann, Wolfgang; Dias, Nelson Filipe Lopes; Stangier, Dominic; Berndt, Jasper; Klemme, Stephan; Kesper, Lukas; Berges, U.; Westphal, C.; Thomann, Carl-Arne; Debus, J.

doi:10.1016/j.diamond.2022.108898

Cited by 2 publications

(3 citation statements)

References 38 publications

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“…The origin for the extended near-surface layer with reduced nanomechanical properties in a-C:Eu 2.4 at.% and a-C:Gd 2.3 is attributed to the surface enrichment in alloying elements in the coatings since, as indicated by X-ray photoelectron spectroscopy (XPS) analyses (see XPS high-resolution spectra in Figure S1), the outermost region of the coatings is enriched in alloying elements ([C]/[Eu] = 14.4 in a-C:Eu 2.4 at.% and [C]/[Gd] = 14.1 in a-C:Gd 2.3 from XPS data acquired at an emission angle of 45°) compared to the bulk of the films ([C]/[Eu] = 39.4 in a-C:Eu 2.4 at.% and [C]/[Gd] = 39.9 in a-C:Gd 2.3 as determined by Rutherford backscattering spectrometrya bulk-sensitive technique). This finding agrees well with the progressive reduction in nanomechanical properties of rare-earth-containing a-C films with the content of the alloying element recently reported by Tillmann et al…”

Section: Resultssupporting

confidence: 93%

Effect of Europium and Gadolinium Alloying Elements on the Tribological Response of Low Hydrogen Content Amorphous Carbon

Edwards,

Lien,

Molina

et al. 2024

ACS Appl. Mater. Interfaces

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Dopants and alloying elements are commonly introduced in amorphous carbon (a-C) materials to tailor their mechanical and tribological properties. While most published studies have focused on doping and alloying a-C coatings with metals or metalloids, doping a-C films with rare-earth elements has only recently been explored. Notably, our understanding of the shear-induced structural changes occurring in rare-earth-element-containing a-C films is still elusive, even in the absence of any liquid lubricants. Here, the friction response of Eu- and Gd-containing a-C films with low hydrogen content deposited by HiPIMS on silicon was evaluated in open air and at room temperature. The load-dependent friction measurements indicated that the introduction of Gd ((2.3 ± 0.1) at.%) and Eu ((2.4 ± 0.1) at.%) into the a-C matrix results in a significant reduction of the shear strength of the sliding interfaces ((41 ± 2) MPa for a-C, (16 ± 1) MPa for a-C:Gd2.3 at.%, and (11 ± 2) MPa for a-C:Eu2.4 at.%). NEXAFS spectromicroscopy experiments provided evidence that no stress-assisted sp3-to-sp2 rehybridization of carbon atoms was induced by the sliding process in the near-surface region of undoped a-C, while the amount of sp2-bonded carbon progressively increased in a-C:Gd2.3 at.% and a-C:Eu2.4 at.% upon increasing the applied normal load in tribological tests. The formation of an sp2-bonded carbon-rich surface layer in a-C:Gd2.3 at.% and a-C:Eu2.4 at.% films was not only proposed to be the origin for the reduced duration of the running-in period in tribological test, but was also postulated to induce shear localization within the sp2-carbon-rich layer and transfer film formation on the countersurface, thus decreasing the interfacial shear strength. These findings open the path for the use of Gd- and Eu-containing a-C even under critical conditions for nearly hydrogen-free a-C films (i.e., humid air).

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Section: Resultssupporting

confidence: 93%

Effect of Europium and Gadolinium Alloying Elements on the Tribological Response of Low Hydrogen Content Amorphous Carbon

Edwards,

Lien,

Molina

et al. 2024

ACS Appl. Mater. Interfaces

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“…On the assumption of a homogeneous MAC, the average defect distance was calculated to be less than 1 nm. [53] Although the overall physical and electrical properties depend on the sp 2 and sp 3 hybridization ratio, doping is a powerful way to improve the inborn properties such as mechanical hardness, [54][55][56][57][58][59][60][61][62][63] diffusion of interstitial atoms, [64][65][66] electrical conductance, [61,62,67,68] optical bandgap, [65,[68][69][70][71][72][73][74] thermodynamic energy control, [62,63,66,75] and electrochemical performance. [76][77][78] To change the properties of a-C, various doping materials (non-metals, [61,62,65,69,75] metals, [55,59,60,64,67,68,70,73,74,…”

Section: Synthesis and Doping Of The A-c Thin Filmsmentioning

confidence: 99%

“…Although the overall physical and electrical properties depend on the sp 2 and sp 3 hybridization ratio, doping is a powerful way to improve the inborn properties such as mechanical hardness, [ 54–63 ] diffusion of interstitial atoms, [ 64–66 ] electrical conductance, [ 61,62,67,68 ] optical bandgap, [ 65,68–74 ] thermodynamic energy control, [ 62,63,66,75 ] and electrochemical performance. [ 76–78 ] To change the properties of a‐C, various doping materials (non‐metals, [ 61,62,65,69,75 ] metals, [ 55,59,60,64,67,68,70,73,74,76–79 ] and metalloids [ 58,63,71,72 ] ) have been attempted in the a‐C thin films ( Table 2 ).…”

Section: Synthesis and Doping Of The A‐c Thin Filmsmentioning

confidence: 99%

Amorphous Carbon Films for Electronic Applications

et al. 2022

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While various crystalline carbon allotropes, including graphene, have been actively investigated, amorphous carbon (a‐C) thin films have received relatively little attention. The a‐C is a disordered form of carbon bonding with a broad range of the CC bond length and bond angle. Although accurate structural analysis and theoretical approaches are still insufficient, reproducible structure–property relationships have been accumulated. As the a‐C thin film is now adapted as a hardmask in the semiconductor industry and new properties are reported continuously, expectations are growing that it can be practically used as active materials beyond as a simple sacrificial layer. In this perspective review article, after a brief introduction to the synthesis and properties of the a‐C thin films, their potential practical applications are proposed, including hardmasks, extreme ultraviolet (EUV) pellicles, diffusion barriers, deformable electrodes and interconnects, sensors, active layers, electrodes for energy, micro‐supercapacitors, batteries, nanogenerators, electromagnetic interference (EMI) shielding, and nanomembranes. The article ends with a discussion on the technological challenges in a‐C thin films.

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Rare-earth modified amorphous carbon films: Effects of erbium and gadolinium on the structural evolution and mechanical properties

Cited by 2 publications

References 38 publications

Effect of Europium and Gadolinium Alloying Elements on the Tribological Response of Low Hydrogen Content Amorphous Carbon

Effect of Europium and Gadolinium Alloying Elements on the Tribological Response of Low Hydrogen Content Amorphous Carbon

Amorphous Carbon Films for Electronic Applications

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