Ar Ion Beam Treatment Research Articles

Flexible W-doped In2O3 films grown on ion beam treated polyethylene terephthalate substrate using roll to roll sputtering

We investigated the effect of Ar ion beam treatment on a polyethylene terephthalate (PET) substrate to grow high-quality flexible W-doped In2O3 (IWO) films using a lab-scale roll-to-roll (RTR) sputtering system at room temperature. The electrical, optical, morphological, and mechanical properties of the flexible IWO films sputtered on the ion beam-treated PET and untreated PET substrates were comprehensively compared. In particular, the mechanical flexibility of the RTR sputtered IWO films was investigated in detail using custom-made bending, rolling, and twisting testers. Based on water contact angle and X-ray photoelectron spectroscopy (XPS) measurements, we found that the surface energy change and decreased C-O and C˭O groups on the PET substrate led to flexible IWO films with improved adhesion and better mechanical properties. In addition, we compared repeating cooling and heating cyclic stability of the flexible thin film heaters with RTR sputtered IWO films before and after ion beam treatment to show feasibility of ion beam treating process during RTR sputtering.

Effects of Ar ion beam treatment on properties of roll-to-roll sputtered Sn-doped In2O3 films on colorless polyimide substrate

We report on the effects of Ar ion beam treatment on the electrical, optical, and mechanical properties of flexible Sn-doped In2O3 (ITO) films grown on colorless polyimide (CPI) by roll-to-roll (R2R) sputtering. Effective Ar ion beam treatment on ITO films led to the reduction of sheet resistance without degradation of optical transmittance of ITO films even though they were prepared at room temperature. In addition, Ar ion beam treatment resulted in crystallization of the R2R-sputtered ITO films without intentional substrate heating. At optimized conditions, the Ar ion beam treated ITO film showed a sheet resistance of 54.6Ω/square and an optical transmittance of 80.1%. A flexible organic solar cell (FOSC) fabricated with the Ar ion beam treated ITO film exhibited a power conversion efficiency (PCE) of 3.137%, which was higher than that of a FOSC made with untreated ITO film. This indicates that the in-situ Ar ion treatment is a promising method for fabrication of crystalline ITO films on flexible substrates without intentional substrate heating in a R2R sputtering process.

The effect of the surface physical properties of polymer substrates on the adhesion and cracking of transparent conductive oxide (TCO) coatings

This work presents the effects of surface physical properties of compliant polymer substrates on the properties of stiff oxide coatings. In this study, polyethylene terephthalate (PET) is selected as the substrate and indium tin oxide (ITO), which is one of the most extensively used transparent conductive oxide (TCO) materials for electrodes in display applications, is sputter deposited on PET varying thickness (hf). Before deposition, PET surface profiles such as roughness and morphology are modified by Ar ion beam treatment. At a fixed beam power, treatment time is carefully controlled to vary only the physical profiles, excluding chemical states of the surfaces. PET and ITO surfaces and interfaces are analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. By fragmentation test, the adhesion and cracking of ITO are evaluated. Our investigation reveals that depositing atoms penetrate into the PET surface due to the low density of PET and the initial surface profiles of PET are not maintained during deposition due to its high compliance. When the effective surface area is highly increased by the ion beam treatment, the polymer surface becomes stiffer since the number of penetrating atoms increases. The rough surface features on the stiffer substrate are less deformed during deposition; hence, interfacial interlocking that improves the adhesion becomes effective throughout the deposition.

Nanoporous structures of polyimide induced by Ar ion beam irradiation

The surface morphology evolution of polyimide (PI) that was treated with an Ar ion beam was explored using a hybrid ion beam system. A hole-like nanostructure formed on PI during the Ar ion beam treatment at a lower fluence, but PI formed 3D porous nanostructures with a mean diameter of ∼90nm at a higher fluence. The chemical binding energy and the composition of the Ar ion irradiated PI were analyzed using FT-IR and XPS spectra, which revealed that the polymer chain scissioning increased with increasing Ar ion treatment duration, i.e., fluence. The surface hardness and the elastic modulus of PI increased from 1.17 to 1.62GPa and 4.06 to 5.41GPa, respectively, with respect to the Ar ion beam treatment duration.

Arイオン打ち込み処理による高誘電率ポリイミドフィルム表面のSEM観察

High-resolution scanning electromicroscopy (SEM) is a powerful technique to elucidate surface information. Because Upilex S® film, a polyimide film (PI film), possesses excellent properties such as chemical and heat resistance, it has been used in many flexible printed board fabrications. When surfaces of the PI film with high permittivity are observed using SEM, the thin film coating of a noble metal by evaporation methods is necessary to avoid charging problems. Such a thin film coating creates artifacts on SEM images. Consequently, high-resolution observation often becomes difficult, especially if we attempt to observe the adsorption of nanoparticles such as Pd-Sn catalysts on the PI film. Surface scientists know empirically that Ar ion beam treatment inhibits charging phenomena of the observed samples.To prevent charging problems during SEM observations, we examined Ar ion implantation for the PI film sample with low acceleration voltage (200—300 V) applied to Ar ion gun. Regarding acceleration voltage at 300 V, high-resolution SEM images of the PI film surface were obtained without any thin film coating of noble metal. Furthermore, elemental analyses of the PI film were enabled by energy dispersive X-ray spectrometry (EDS) performed with high current.

Nano-embossed structure on polypropylene induced by low energy Ar ion beam irradiation

The surface morphology evolution of polypropylene (PP) irradiated with an Ar ion beam was explored using a hybrid ion beam system. PP formed the emboss-like nanostructure of ∼ 50 nm induced by the Ar ion beam treatment for shorter ion beam treatment times, while the emboss-like structure was transited into a 3-D long nanofiber-like nanostructure for longer treatment times. The Fourier transform infrared spectra revealed that the polymer chain cross-linking increased with increasing ion treatment time, while the Raman analysis showed that the conducting amorphous carbon increased on the surface of PP. The surface hardness and plane strain modulus of the PP decreased from 0.11 to 0.07 GPa and from 1.75 to 1.26 GPa, respectively, with respect to the Ar ion beam treatment time due to the surface nanostructures formed by the Ar ion beam.

The Morphology and Mechanical Properties of Polycarbonate/Acrylonitrile Butadiene Styrene Modified by Ar Ion Beam Irradiation

AbstractThis study examined the surface morphological evolution of polycarbonate and acrylonitrile butadiene styrene (PC/ABS) irradiated with an Ar ion beam using an ion beam system. PC was not affected by the Ar ion beam treatment at a lower ion beam treatment times but the ABS portion formed a foam‐like nanostructure at the surface. On the other hand, both PC and ABS formed nanostructures with length of 100 to 120 nm and a mean diameter of ≈35 nm at longer beam treatment times. The Raman and FTIR spectra revealed polymer chain scissioning. Nanoindentation showed that the hardness and elastic modulus of the PC/ABS decreases from 0.22 to 0.18 GPa and from 3.39 to 2.98 GPa, respectively with increasing Ar ion beam treatment time due to the surface nano‐structures formed by Ar ion beam.magnified image

Improvement of adhesion of DLC coating on nitinol substrate by hybrid ion beam deposition technique

Diamond-like carbon (DLC) films were prepared for a protective coating on nitinol substrate by hybrid ion beam deposition technique with an acetelene as a source of hydrocarbon ions. An amorphous silicon (a-Si) interlayer was deposited on the substrates to ensure better adhesion of the DLC films followed by Ar ion beam treatment. The film thickness increased with increase in ion gun anode voltage. The residual stresses in the DLC films decreased with increase in ion gun anode voltage and film thickness, while the stress values were independent of the radio frequency (RF) bias voltage. The adhesion of the DLC film was improved by surface treatment with argon ion beam for longer time and by increasing the thickness of a-Si interlayer.

Improvement of electron field emission from carbon nanotubes by Ar neutral beam treatment

To improve the field emission properties of screen printed carbon nanotube (CNT) films, an Ar neutral beam was used as one of the surface treatment techniques and the CNT field emission characteristics after the treatment were compared with those after Ar ion beam treatment. The Ar neutral beam treatment enhanced the field emission properties of the CNTs and by decreasing the turn-on field and by increasing emission sites. When the field emission properties were measured after the treatment for 10 s with an energy of 100 eV, the turn-on field decreased from 1.7 to 0.9 V/μm while that after the ion beam treatment increased from 1.7 to 2.8 V/μm showing damage of exposed CNTs due to the intensive bombardment by the positive ions in the beam. The neutral beam treatment appeared to expose more CNT field emitters from the CNT paste without cutting or severely damaging the already exposed long CNT emitters because there were no charged particles in the beam.

Performance Enhancement of Organic Thin-Film Transistors by Low-Energy Argon Ion Beam Treatment of Gate Dielectric Surface

In this paper, we report the effects of an argon (Ar) ion beam surface treatment of a SiO2 dielectric layer in organic thin-film transistors. We compared the electrical properties of pentacene deposited on a SiO2 layer after O2 plasma or Ar ion beam treatment and characterized the states of the surface of the dielectric by atomic force microscopy and X-ray photoelectron spectroscopy (XPS). For the sample that was subjected to O2 plasma cleaning, mobility increased significantly but the current on/off ratio was found to be very low. In contrast, the Ar-ion-beam-treated sample showed a very high current on/off ratio as well as a moderately improved mobility. The comparison of the XPS data taken from the dielectric surfaces after the two treatments revealed that the ratio between O–Si bonds and O–Si–O bonds was much higher in the O2-plasma-cleaned surface than in the Ar-ion-beam-treated surface. These results demonstrate that our surface treatment using an inert gas, Ar, enables an effective surface cleaning while keeping surface damage minimal and also marked improvements on electrical performances of organic thin-film transistors (OTFTs) were achieved as a consequence of improved surface conditions.

Controlled growth of nano-size metal clusters on polymers by using VPD method

A completely dry technique (VPD) for the preparation of a metal cluster onto a polymer surface or between two polymer layers opens up very good possibilities to control the two dimensional dispersion of the metal clusters and their size during variation of the deposition parameters or the polymer surface treatment. The kinetics of heterogenous nucleation and the growth of nano-size metal clusters (Ni, Ag, Cu, Au) on polymers with different chemical composition (PMDA-ODA polyimide, polystyrene and Teflon AF) are studied by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). In contrast to preferred nucleation and significantly incomplete condensation on the surface of Teflon AF and PS random nucleation and well defined cluster distribution was observed on PMDA-ODA polyimide. It was shown that cluster size and cluster distribution can be influenced in a wide range (some order of magnitude) by the variation of the preparation parameters. Ar ion beam treatment of polymers with low ion dose (10 12–10 16 cm −2) as well as predeposition of a trace amount of a reactive metal can be successfully used to prepare a definite cluster structure due to creation of adsorption sites on polymer surface.