Oxygen Plasma Treatment Time Research Articles

Influence of oxygen plasma treatment on structural and spectral changes in gold nanorods immobilized on indium tin oxide surfaces.

Oxygen plasma treatment is commonly used to sterilize gold nanoparticles by removing chemical contaminants from their surface while simultaneously inducing surface activation and functionalization of nanoparticles for biological, electrocatalytic, or electrochemical studies. In this study, we investigate the influence of oxygen plasma treatment on structural and localized surface plasmon resonance (LSPR) spectral changes of anisotropic gold nanorods (AuNRs) immobilized on an indium tin oxide (ITO) glass substrate. Unlike AuNRs deposited on a glass slide, no noticeable structural change or deformation of AuNRs on ITO was observed while increasing the oxygen plasma treatment time. This result indicates that ITO provides structural stability to AuNRs immobilized on its surface. Additionally, single-particle scattering spectra of AuNRs showed the broadening of LSPR linewidth within 60s of oxygen plasma treatment as a result of the plasmon energy loss contributed from plasmon damping to ITO due to the removal of capping material from the AuNR surface. Nevertheless, an increase in the surface charge on the AuNR surface was observed by narrowing the LSPR linewidth after 180s of plasma treatment. The electrochemical study of AuNRs immobilized on ITO electrodes revealed the surface activation and functionalization of AuNRs by increasing plasma treatment. Hence, in this study, a significant understanding of oxygen plasma treatment on AuNRs immobilized on ITO surfaces is provided.

Oxygen plasma treatment time induced hydrophilicity of polydimethylsiloxane (PDMS) thin films for liquid lenses application

Poly (dimethylsiloxane) (PDMS) has excellent physical and chemical properties, which are widely used for hydraulic fluids, lithography, and many applications. However, the hydrophobic property of PDMS limits some applications such as the insulating protective layer of electrodes for adaptive liquid lens devices. The oxygen plasma treatment can improve the hydrophilic of the PDMS surface, which is the appropriate surface for liquid lens application. In this paper, we present the oxygen plasma treatment time dependence of the hydrophilicity on the surface of PDMS thin films. The different thicknesses of PDMS thin films were treated by oxygen plasma at different treatment times. The contact angle of glycerol on the PDMS thin films with a thickness of 15 ± 1.17 µm and 43 ± 1.44 µm was initially 104 and 76.7°, respectively. As the treatment time increased, the contact angles of both PDMS thicknesses were gradually decreased. The results show that at an oxygen plasma power of 200 W, an extended treatment time would allow the PDMS surface to be hydrophilic. Moreover, the hydrophilic transformation rate of PDMS thin film is rather more rapid than that of PDMS thick film. The oxygen plasma treatment time and thickness of PDMS film are the key conditions for the adaptive liquid lens application.

Synergy of Oxygen Plasma and Al2O3 Atomic Layer Deposition on Improved Electrochemical Stability of Activated Carbon-Based Supercapacitor

As a conventional electrode material of electric double-layer capacitors (EDLC), activated carbon (AC) still faces challenges to exhibit high capacitance. To address this problem, herein, we introduce a combined method of oxygen plasma and Al2O3 tomic layer deposition (ALD) on AC electrodes to reduce the impedance and improve the cycle stability of EDLC. The defect structure can be precisely designed by simply tuning the oxygen-plasma treatment time, thereby affecting the microstructures of AC electrode. Such a tactic permits the first-operated AC electrode with more defects and the ALD passivation of AC resulting in an outstanding rate performance for the device (40.6 F g–1 at 5 mA cm–2, 20.1 Fg–1 at 100 mA cm–2) and cycling stability (∼90% retention after 5,000 cycles). This benefit from the synergistic effect of defects from doped oxygen and stable aluminum oxide layer on the electrode surface. This work delivers a feasible strategy to construct a stable AC material with superior cycling performance for supercapacitor.

Single-particle study: effects of oxygen plasma treatment on structural and spectral changes of anisotropic gold nanorods.

Oxygen plasma treatment is a common method for removing the surfactant capping material from gold nanoparticles, improving their functionalization and lowering their cytotoxicity for biological studies. This single-particle study investigates the effects of oxygen plasma treatment on the structural and localized surface plasmon resonance (LSPR) spectral variations of anisotropic gold nanorods (AuNRs). Single AuNRs subjected to different plasma treatment times were characterized by scanning electron microscopy and dark-field microscopy. The AuNR length was a gradually decreasing function of plasma treatment time. After 120 s of plasma treatment, the aspect ratio of the AuNRs was reduced by a major structural deformation. Furthermore, increasing the plasma treatment time gradually broadened the LSPR linewidth of the single AuNRs. This trend was attributed to the decreased aspect ratio and the increased plasmon damping. These results provide vital and fundamental information on the relationship among plasma treatment time, structural change, and LSPR damping at the single-particle level.

Probing the Growth Improvement of Large-Size High Quality Monolayer MoS₂ by APCVD.

Two-dimensional transition metal dichalcogenides (TMDs) have attracted attention from researchers in recent years. Monolayer molybdenum disulfide (MoS2) is the direct band gap two-dimensional crystal with excellent physical and electrical properties. Monolayer MoS2 can effectively compensate for the lack of band gap of graphene in the field of nano-electronic devices, which is widely used in catalysis, transistors, optoelectronic devices, and integrated circuits. Therefore, it is critical to obtain high-quality, large size monolayer MoS2. The large-area uniform high-quality monolayer MoS2 is successfully grown on an SiO2/Si substrate with oxygen plasma treatment and graphene quantum dot solution by atmospheric pressure chemical vapor deposition (APCVD) in this paper. In addition, the effects of substrate processing conditions, such as oxygen plasma treatment time, power, and dosage of graphene quantum dot solution on growth quality and the area of the monolayer of MoS2, are studied systematically, which would contribute to the preparation of large-area high-quality monolayer MoS2. Analysis and characterization of monolayer MoS2 are carried out by Optical Microscopy, AFM, XPS, Raman, and Photoluminescence Spectroscopy. The results show that monolayer MoS2 is a large-area, uniform, and triangular with a side length of 200 μm, and it is very effective to treat the SiO2/Si substrate by oxygen plasma and graphene quantum dot solution, which would help the fabrication of optoelectronic devices.

Influence of non-thermal plasma treatement on the adsorption of a stimuli-responsive nanogel onto polyethylene terephthalate fabric

This paper presents an in-depth study of the surface modification of polyethylene terephthalate fabric (PET) with non-thermal plasma and temperature- and pH-responsive nanogel (PNCS) to impart smart thermoregulation properties. To increase the adsorption of the PNCS nanogel onto the PET, ammonia and oxygen plasma and a combination of both plasma gases were used. Chemical changes caused by the plasma treatment were investigated using X-ray photoelectron spectroscopy (XPS), morphological changes were determined using scanning electron microscopy (SEM) and the swelling and de-swelling ability was determined by measuring the moisture content at 20 and 40 °C. The greatest deposition of the PNCS nanogel, with unimpaired swelling ability, was found on the oxygen-plasma-treated samples, as they had the highest O/C ratio. Meanwhile, the least promising results were found for the samples treated with a combination of oxygen and ammonia plasma, where the highest concentration of nitrogen was present on the fibre surface. Since the treatment with oxygen plasma proved to be the most effective method, different exposure times to the oxygen plasma, namely, 10, 30 and 60 s, were studied in the second part of this study. The optimal oxygen plasma treatment time was found to be 30 s, where the greatest deposition and unhindered swelling/de-swelling ability of the PNCS nanogel on the PET fabric was achieved.

Tailoring properties of reduced graphene oxide by oxygen plasma treatment

We report an easily controllable, eco-friendly method for tailoring the properties of reduced graphene oxide (rGO) by means of oxygen plasma. The effect of oxygen plasma treatment time (1, 5 and 10 min) on the surface properties of rGO was evaluated. Physicochemical characterization using microscopic, spectroscopic and thermal techniques was performed. The results revealed that different oxygen-containing groups (e.g. carboxyl, hydroxyl) were introduced on the rGO surface enhancing its wettability. Furthermore, upon longer treatment time, other functionalities were created (e.g. quinones, lactones). Moreover, external surface of rGO was partially etched resulting in an increase of the material surface area and porosity. Finally, the oxygen plasma-treated rGO electrodes with bilirubin oxidase were tested for oxygen reduction reaction. The study showed that rGO treated for 10 min exhibited twofold higher current density than untreated rGO. The oxygen plasma treatment may improve the enzyme adsorption on rGO electrodes by introduction of oxygen moieties and increasing the porosity.

Effect of Low Temperature Plasma Treatment on the Dyeability of Regenerated Bamboo/Cotton Blended Fabrics

In this research, regenerated bamboo (viscose)/cotton blended fabrics were treated with low temperature plasma under various treatment conditions (i.e., oxygen flow rate, jet-to-substrate distance, and plasma treatment time) to evaluate how these parameters influenced fabric dyeing properties. It was shown that low temperature plasma treatment can modify polymer surfaces and change the substrate's properties, such as wettability. In this study, plasma-treated fabrics were dyed with mono-functional and bi-functional reactive dyes to check for changes in CIELAB, Δ E*, and color yield values. The study concluded that color yield of the plasma-treated fabric was better when dyed to a color depth of 3%.

Surface Modification of C3N4 through Oxygen-Plasma Treatment: A Simple Way toward Excellent Hydrophilicity

We developed a universal method to prepare hydrophilic carbon nitrogen (C3N4) nanosheets. By treating C3N4 nanosheets with oxygen plasma, hydroxylamine groups (N-OH) with intense protonation could be introduced on the surface; moreover, the content of N-OH groups increased linearly with the oxygen-plasma treatment time. Thanks to the excellent hydrophilicity, uniformly dispersed C3N4 solution were prepared, which was further translated into C3N4 paper by simple vacuum filtration. Pure C3N4 paper with good stability, excellent hydrophilicity, and biocompatibility were proved to have excellent performance in tissue repair. Further research demonstrated that the oxygen-plasma treatment method can also introduce N-OH groups into other nitrogen-containing carbon materials (NCMs) such as N-doped graphene, N-doped carbon nanotube, and C2N, which offers a new perspective on the surface modification and functionalization of these carbon nanomaterials.

Morphological evolution of self-deposition Bi2Se3 nanosheets by oxygen plasma treatment.

Bi2Se3 nanosheets were successfully synthesized by a microwave-assisted approach in the presence of polyvinylpyrroli done at a temperature of 180 °C for 2 h. The thin film was prepared on a silicon wafer via a self-deposition process in a Bi2Se3 nanosheet ink solution using the evaporation-induced self-assembly method. The structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy, and Raman spectroscopy. The highly uniform Bi2Se3 particles could be formed by controlling the oxygen plasma treatment time. After the plasma pretreatment from 10 to 20 s, the surface of Bi2Se3 film evolved from the worm-like structure to particles. The highly uniform thin film was formed on further increasing the plasma treatment time, which is consistent with the observed SEM results. Several important processes can result in the morphological evolution of Bi2Se3 nanosheets: (1) formation of Bi2Se3 oxide layer; (2) self-assembly of oxide nanoparticles under the action of high-energy oxygen plasma; and (3) electrostatic interaction and etching mechanism.

Etchless Fabrication of Cu Circuits Using Wettability Modification and Electroless Plating

Cu circuits were successfully fabricated on flexible PET(polyethylene terephthalate) substrates using wettability difference and electroless plating without an etching process. The wettability of Cu plating solution on PET was controlled by oxygen plasma treatment and SiOx-DLC(silicon oxide containing diamond like carbon) coating by HMDSO(hexamethyldisiloxane) plasma. With an increase of the height of the nanostructures on the PET surface with the oxygen plasma treatment time, the wettability difference between the hydrophilicity and hydrophobicity increased, which allowed the etchless formation of a Cu pattern with high peel strength by selective Cu plating. When the height of the nanostructure was more than 1400 nm (60 min oxygen plasma treatment), the reduction of the critical impalement pressure with the decreasing density of the nanostructure caused the precipitation of copper in the hydrophobic region.

A Study on the Adhesion Properties of Reactive Sputtered Molybdenum Thin Films with Nitrogen Gas on Polyimide Substrate as a Cu Barrier Layer.

NiCr, Mo, and Mo-N thin copper diffusion barrier films are deposited on 200 um thick polyimide films spin-coated on glass substrates by dc reactive magnetron sputtering. The adhesion forces for three systems are measured by micro-scratch test analysis depending on oxygen plasma pretreatment, sputtering power density, moisture contents, and post annealing treatment. The values of adhesion forces for the three systems are linearly proportional to the oxygen plasma treatment time. As deposition power density increases, measured adhesion forces also increase. The existence of moisture adsorbed in the polymer substrate prior to initiating the sputtering process significantly reduces the adhesion force for all systems. Post annealing treatment at 150 degrees C for 12 hours after sputtering also deteriorates the adhesion between the barrier films and polymer substrate. Auger electron spectroscopy reveals that adhesion forces are significantly dependent on the types of compounds formed at the barrier layer/polymer interface. Changes in the adhesion properties of the MoN system as a function of the nitrogen content are explained in terms of the mechanical stability of the MoN(x)O(y) interface layer on the polymer substrate.

Using oxygen-plasma treatment to improve the photoresponse of Mg0.18Zn0.82O/p-Si heterojunction photodetectors

Oxygen-plasma treatment was carried out on Mg0.18Zn0.82O thin films, grown on Si substrates, and the effects of oxygen-plasma treatment on Mg0.18Zn0.82O/p-Si heterojunction photodetectors (HPDs) were studied. It was found that with increasing of oxygen-plasma treatment time, the leakage current of Mg0.18Zn0.82O/p-Si HPDs is reduced. As compared to without treatment, the leakage current of treated HPDs is drastically decreased by ∼180 times and the rectification ratio improved greatly from 94.1 to 32,500. All Mg0.18Zn0.82O/p-Si HPDs appear about the same visible responsivity, in contrast the ultraviolet (UV) responsivity increases with longer oxygen-plasma treatment time. The UV (320 nm) responsivity increases from 0.56 A/W to 4.21 A/W for the untreated and 50-min treated HPDs, respectively. However a reduced UV responsivity is observed for the 70-min-treated HPDs, attributing to the oxygen atoms saturate at 50-min treatment time. The extended treatment time (over 50 min) causes more plasma bombardment on the Mg0.18Zn0.82O surface, thus degrading the responsivity. Two issues leads to the reduced leakage current and enhanced UV responsivity. One is that the introduced oxygen atoms fill the oxygen vacancy, and hence suppress the oxygen-vacancy-related defects. Another issue is that the excess oxygen atoms build a stable MgO film on the Mg0.18Zn0.82O surface, effectively passivating the HPDs.

Development of crystalline–amorphous parylene C structure in micro- and nano-range towards enhanced biocompatibility: the importance of oxygen plasma treatment time

The crystalline–amorphous parylene C structure was fabricated by Chemical Vapour Deposited (CVD) and functionalised in the micro- and nano-range with the oxygen plasma treatment.

Enhancement of gas sensor response of nanocrystalline zinc oxide for ammonia by plasma treatment

Abstract The effect of oxygen plasma treatment on nanocrystalline ZnO thin film based gas sensor was investigated. ZnO thin films were synthesized on alkali-free glass substrates by a sol–gel process. ZnO thin films were treated with oxygen plasma to change the number of vacancies/defects in ZnO. The effect of oxygen plasma on the structural, electrical, optical and gas sensing properties was investigated as a function of plasma treatment time. The results suggest that the microstructure and the surface morphology can be tuned by oxygen plasma treatment. The optical transmission in the visible range varies after the oxygen plasma treatment. Moreover, it is found that the oxygen plasma has significant impact on the electrical properties of ZnO thin films indicating a variation of resistivity. The oxygen plasma treated ZnO thin film exhibits an enhanced sensing response towards NH 3 in comparison with that of the as-deposited ZnO sensor. When compared with the as-deposited ZnO film, the sensing response was improved by 50% for the optimum oxygen plasma treatment time of 8 min. The selectivity of 8 min plasma treated ZnO sensor was also examined for an important industrial gas mixture of H 2 , CH 4 and NH 3 .

Effects of Oxygen-Plasma Treatment Time on the Properties of UHMWPE Fiber

Ultra-high-molecular-weight polyethylene (UHMWPE) fibers were treated by low temperature oxygen-plasma. The effects of oxygen-plasma treatment time on the properties of UHMWPE have been investigated. The wetting ability and roughness were increased significantly after the treatment. While, the tensile strength at break of UHMWE fibers were decreased with the treatment time. The optimum plasma treatment time is 2min.

Deposition of platinum on oxygen plasma treated carbon nanotubes by atomic layer deposition

Platinum nanoparticles were deposited on oxygen plasma treated carbon nanotubes (CNTs) by atomic layer deposition (ALD). The treatment time with oxygen plasma generated by microwaves under a power of 600 W varied from 5 to 20 s. The number of ALD cycles was controlled at 5–125. X-ray photoelectron spectroscopic analysis indicated that oxygen plasma can graft oxygen-containing functional groups to the CNT surface to act as nucleation sites for growth of Pt nanoparticles. Formation of very uniform and well distributed Pt nanoparticles of a size of 1.60–4.80 nm was achieved. The growth rate of Pt nanoparticles could be controlled by the number of ALD cycles and oxygen plasma treatment time. This offers a dry process to deposit well-dispersed metallic nanoparticles on selected support materials.

Tetragonal or monoclinic ZrO2 thin films from Zr-based glassy templates

The authors report on the selective formation of pure tetragonal or mixed tetragonal-monoclinic ZrO2 films by means of post-growth oxygen plasma treatment of Zr-based Zr–Cu ternary or quaternary metallic glassy (MG) films containing minor additions of Al, Ti, and Si. It came out that the choice of the third and/or fourth element in the MG template, in conjunction with oxygen plasma conditions and treatment time, determine the crystal structure and the surface morphology of the ZrO2 films. The authors found that the oxidation of the Zr–Cu MG template resulted in mixed tetragonal-monoclinic ZrO2 film with rather rough surface, whereas in the case of Al additions smooth surfaces of pure tetragonal or mixed tetragonal-monoclinic ZrO2 films were grown after short and long treatment times, respectively. In addition, oxygen plasma treatment of MG templates containing Ti and/or Si minor additions resulted in mixed tetragonal-monoclinic ZrO2 films, the doping element and the treatment times adjusting besides the concentration of each phase also the surface morphologies, which can vary from cones, in the case of Ti addition, to nanosponge and completely rough structures in Si ternary and Si/Ti quaternary systems, respectively. These findings suggest a quick, amenable, and low cost method of two-step industrial scale processing for selective growth of tetragonal and/or monoclinic ZrO2 with specific surface morphology.

Large-Area Bowtie Nanoantenna Arrays Fabricated with Economic Oxygen Plasma-Assisted Nanosphere Lithography

Bowtie nanoantenna arrays were fabricated using plasma-assisted nanosphere lithography. The gap of each bowtie nanoantenna was precisely controlled by tuning the oxygen plasma treatment time, and gap distance as small as 30 nm was successfully fabricated. The occurrence of plasmon coupling and the functionality of the bowtie nanoantenna arrays were experimentally and theoretically verified. The plasma treatments help to change the size and gap distance of the nanoparticle arrays to match a specific surface plasmon resonance wavelength. The fabricated nanoantenna array covered a large area (∼1 cm2) and was suitable for large-scale fabrication with simple scale-up of the fabrication instruments, which should lead to novel new applications.

Development of enhancement mode AlN/GaN high electron mobility transistors

Enhancement mode AlN/GaN high electron mobility transistors (HEMTs) were fabricated from originally depletion-mode structures using oxygen plasma treatment on the gate area prior to the gate metallization. Starting with a depletion mode AlN/GaN HEMT, the threshold voltage of the HEMT could be shifted from −3.2 to 1 V depending on the oxygen plasma treatment time to partially convert the AlN barrier layer into Al oxide. The gate current was reduced and the current-voltage curves show metal-oxide semiconductor diodelike characteristics after oxygen plasma treatment.