九州シンクロトロン光研究センター
県有ビームライン利用報告書
課 題 番 号 ： 2106055S

Ｂ Ｌ 番 号 ： 12（様式第 5 号）

同軸型アークプラズマ堆積法によりバイアス印加下で堆積されたナ ノ ダ イ ヤ モ ン ド 膜 の 化 学 結 合 構 造 (II)Chemical bonding structure of nanodiamond films deposited under negative biases
by coaxial arc plasma deposition (II)ア リ モ ハ メ ド ア リ ，イ ス ラ ム ナ イ ム ，齊 藤 誠 志 郎 ，ア ブ デ ル ラ ー マ ン ザ キ リ ア ，
楢木野 宏，吉武 剛

Ali M. Ali, Eslam Naeim, Seishiro Saito, Abdelrahman Zkria, Hiroshi Naragino,
and Tsuyoshi Yoshitake
九州大学大学院総合理工学研究院

Faculty of Engineering Sciences, Kyushu University
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１．概要（注：結論を含めて下さい）
Ultrananocrystaline diamond (UNCD)/amorphous carbon (a-C) composite(UNCD/a-C) films were deposited on negatively biased cemented carbide (WC-Co)
substrates by coaxial arc plasma deposition, and the effects of negative bias on thegrowth and mechanical properties of the films were studied. The negative bias
voltage was applied in pulsed process at 10, 50, and 90 kHz. The 62 GPa hardness
films were deposited at a thickness of 8.8 µm, which is more than an order ofmagnitude more than that of comparably hard diamond like carbon films depositedby arc ion plating deposition. In addition, the deposition rate evidently increased
under the negative bias. This might be because the negative bias enhances theattraction of positively charged carbon species to the substrates, which results inenhanced film adhesion on the substrates and the release of film internal stresses.

２．背景と目的
Coaxial arc plasma deposition (CAPD) has been recently employed as a promising physicalvapor deposition technique to fabricate artificially structured nanomaterials speciallynanodiamond composite (NDC) films for hard coating applications [1]. CAPD offers many pros
over chemical vapor deposition growth techniques, which has essentially employed fornanodiamond films deposition [2]. Like lower deposition temperature, higher growth rate, andenhanced control of morphology and thickness, as well as its applicability to versatile substrates
without surface pretreatments or seeding process, are the main advantages of CAPD to mention.
To improve the deposition ability of the CAPD system and enhance the mechanical andstructural properties of the deposited films a development of coating systems was driven bycontrolling the deposition process. Energy of deposited species is a major factor in CAPD, which
controlling the adhesion strength and film properties. The energy of the deposited species, which
can be controlled by negative substrate bias, is necessary to compensate for the deeper
penetration of the arriving species as their energies increase [3]. Investigate the influence ofthisese parameter on the deposition process, structural, and mechanical properties of thedeposited nanodiamond composite films, are the aim of this study.
３．実験内容（試料、実験方法、解析方法の説明）
UNCD/a-C films were deposited at different substrate bias frequencies using coaxial arc
plasma deposition (CAPD) equbied with a graphite target. Tungsten carbide (WC-Co K-type wasused as substrates. The deposition was conducted under a substrate bias voltage of −80 V andfrequencies of 10, 50, and 90 kHz with a duty cycle of 60%. To investigate the influence of bias
frequency on the plasma energy, a triple Langmuir probe diagnostic system was adopted tomeasure the electron temperature of the generated arc plasma under different bias frequencies.
The effects of the substrate bias voltage on the deposition process, mechanical and structuralproperties of the films were investigated by nanoindentation and Raman spectroscopy,respectively.
４．実験結果と考察
Deposition process and films properties strongly depend on the plasma energy and flux ofdeposited carbon species. shows the 3D laser recorded surface morphology and the X-ray
photoelectron spectra of the chemical surface composition of the UNCD/a-C films deposited atdifferent substrate bias frequencies. The 3D images were discernible that the film surface has arandom distribution of particles like clusters. The surface roughness indicated that all depositedfilms exhibited relatively smooth surfaces. The surface roughness root mean square (RMS) of thefilm deposited at 10 kHz was around 0.182 μm and this value gradually increase up to 0.207 μm
by increasing the substrate bias frequency. Accordingly, accelerating the carbon species toward
the substrate at low substrate bias frequency smoothens the surface of the deposited films. Thisbehavior has been reported previously and it is attributed to the decreasing the shadowing effectby substrate biasing [4]. This observed light smoothing of the film surface might be due to thedissipation of the acceleration excessive energy induced by the applied negative bias andenhanced mobility of adatoms which evidently flattened the surface.
The chemical composition of the film surface was examined by X-ray photoelectron spectroscopy
as shown in (d), (e) and (f). Intense C 1s and O 1s peaks are observed at binding energies of 284.5and 532.5 eV, respectively [5]. The C 1s peaks originated from the carbon atoms of the UNCD/a-Cfilms. The O 1s peaks are due to the adsorption of oxygen when the film surface exposed to theFigure 1 Three-dimensional topographic laser microscopic images of UNCD/a-C films deposited at
substrate bias frequency of (a) 10, (b) 30, (c) 90 kHz with a surface elemental composition investigated by
X-ray photoelectron spectroscopy in (d), (e), (f), respectively.

atmospheric oxygen after the deposition. The relative intensity of the O 1s peak graduallyenhanced with increasing the substrate bias frequency as shown in Figure 1(f). The increased
ratio of oxygen can be linked to the high surface roughness of the films deposited at high bias
frequency. The high surface roughness means increasing the probability of vacancies and cavities
capable of keeping more oxygen atoms.
５．今後の課題
The influences of bias frequency on the properties of ultrananocrystalline diamond/ amorphous
carbon (UNCD/a-C) films deposited on WC-Co substrates using coaxial arc plasma deposition has
investigated. The negative bias can attract more positive ions to bombard the substrate surface,leaving behind a much denser structure. The surface smoothness and overall oxidation adsorbedon the film surface were improved by applying the negative bias voltage.
６．参考文献[1] A. M. Ali et al., Applied Physics. Express 13, 065506 (2020).
[2] H. Naragino et al., Japanese Journal of Applied Physics 55, 030302 (2016).
[3] A. M. Ali et al., Diamond and Related Materials 96, 67 (2019).
[4] M. Saeed et al., Applied Surface Science 528, 146966 (2020).
[5] A. M. Ali et al., Surface & Coatings Technology 417, 127185 (2021).

７．論文発表・特許（注：本課題に関連するこれまでの代表的な成果）
 A. M. Ali et al., Diamond and Related Materials 96, 67 (2019).
 A. M. Ali et al., Appl. Phys. Express 13, 065506 (2020).
 A. M. Ali et al., Surface & Coatings Technology 417, 127185 (2021) .
８．キーワード（注：試料及び実験方法を特定する用語を２～３）
UNCD/a-C films, Negative bias, Coaxial arc plasm deposition.
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論文（査読付）発表の報告（報告時期：2023 年 3 月）