Yousefi H.R.

Article富山大学地域連携推進機構産学連携部門ベンチャー・ビジネス・ラボラトリー年報, 平成21年度, 2009, Page 94-96departmental bulletin pape

Yousefi, H.R.

University of Toyama Repository

Abstract Diamond田likeCarbon (DLC) Film deposition Using Toyama Dense Plasma Focus Post圃doctoralfellow, H.R. Yousefi The pulsed intense ion beam, emitted from a dense plasma focus (DPF) discharges performed with hydrogen gas, has been used to ablate the graphite target depositing diamond-like carbon (DLC) films on Si substrates. The substrates were mounted on a holder, which allowed for deposition at positions between nom1al and 20"。妊：.normalto the target. The samples were removed for analysis after 10 and 20 shots. Nano-particles were observed in the films by a field-emission scanning electron microscope. Raman spectra indicate that sample deposited at 20 off-normal with 20 shots possesses the highest sp"' content among the samples. The film deposited at this position was also found has the highest hardness. Introduction The dense plasma focus (DPF) is well known as a compact and an efficient pulsed source of X-raysヲneutrons, relativistic electrons and energetic ion beams. The current sheath dynamics in DPF allows the formation of high temperature (1-2 keV) and high-densi守（～1025-1026m-3) plasma column at the end of radial collapse phase. The plasma column then disintegrated due to plasma instabilities, which generate energetic ions and relativistic electrons. The DPF device has been experimentally proved to be able to emit ions of characteristic energy from hundreds of ke V to tens of Me V.The plasma jet and energetic electrons are responsible for the ablation of target material and the ablated material can be deposited on the substrate. Diamond-like carbon (DLC) is a typical form of amorphous carbon consisting of a mixture of sp3 and sp2 fractions. The beneficial properties of DLC are the sp3 constituents that make DLC mechanically hardヲ in企ared(IR) transparent, and chemically inert. The first DLCs were prepared as thin films by Aisenberg and Chabot using ion beam deposition. So far several techniques have been developed to deposit DLC films by different types of chemical vapor deposition (CVD) and physical-vapor deposition (PVD) methods, such as filament胃assistedchemical vapor deposition, ion-assisted deposition filtered cathodic vacuum arc, microwave plasma-assisted deposition, mass-selected ion beam deposition, and pulsed laser deposition .Most approaches to obtain DLC need rapidly cooling process. It is well known that DPF is not only a system with rapid cooling processes, but also a promising source in this respect offering room temperature deposition of thin films having be枕eradhesion to the substrate owing to the broad energy spectrum of its ion streams. Moreover, as a source of pulse energy beams, the DPF device shares some common characteristics with respect to pulsed laser deposition (PLD), including high deposition rate, possible film deposition under a reactive background gas pressure , direct ion irradiation process ,deposition of materials having high melting temperature as compared to the continuous deposition techniques . As a consequence, there are good reasons to believe that high deposition rate of DLC films with better adhesion to the substrate can be actualized by DPF device. Besides, 97 ?????????匂均砂ι吋均時肱 …骨 substrate 44.8μ F? 30kv Fig. 1. The schematic of the DPF device employed for DLC film deposition. Experimental procedure High puri句fgraphite disc of 50 mm diameter and 5 mm thickness was used. as a target and was placed into the chamber at 150 mm企omanode tip along axial direction. The carbon films were deposited on commercially available one sided polished Si (100) wafer, which was cut into square shape biscuits of 15 mm×15 mm and then was cleaned ultrasonically in acetone. The substrates were blown-dry and then set into the chamber with the help of a sample hold紅、 bearingtwo samples at angular position of normal and 20° off normal to the target. By this design, deposition of varied carbon ion energies in the carbon ablation plasma was analyzed. Conclusions Carbon films produced through the ablation of graphite by intense pulsed ion beam using a 20 kJ DPF device is reported. Copper impurities, which were found in XRD results, were subsequently observed in SEM micrographs. All the films showed reasonably smooth surface with nano幽sizedagglomerates. Raman shift and band intensity inferred that sp3 content in the sample of 20 shots off-n01mal should be the highest. Hardness results indicate that sample of 20 shots off-normal owns the highest plastic har出ies.Hardness results also showed very good agreement with SEM and Raman results. All the preliminary evidencesヲ obtainedfrom SEM, Raman, hardness results, suggest that over-heating process may reduce sp3 content of the film and finally bring poor hardness to the sample of 20 shots normal. Lower ion energy flux at the position of 2ff 。妊：.normalseems to be more suitable for DLC film growth. Not only ion energy flux, but also the number of DPF shots plays an important role in controlling the grain size, thicknessヲandmany other properties of the films 98 

Diamond-like Carbon (DLC) Film deposition Using Toyama Dense Plasma Focus

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Diamond-like Carbon (DLC) Film deposition Using Toyama Dense Plasma Focus

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