Effect Of Oxygen Plasma Research Articles

Effect of oxygen plasma on ITO surface and OLED physical properties

In this study, we treated the surface of indium tin oxide (ITO) with oxygen plasma. In doing so, ITO thin films were exposed to oxygen plasma. This treatment was performed with plasma oxygen at 4, 6, and 8 min. The ITOs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), and ultraviolet-visible (UV–vis) spectroscopy. These characterizations showed that the structure and transparency were only slightly changed by the treatment. However, the plasma treatment improved the surface morphology and changed the thickness and electrical properties of the ITOs. The surface roughness of the ITOs was reduced from 2.34 to 0.899 nm by the treatment. With an 8-min plasma treatment, the strength of the sheet without ITO treatment increased from 12.61 to 13.97 Ω/□.The organic light-emitting diodes (OLEDs) with glass/ITO/PEDOT:PSS/Alq3/Al structure were fabricated. Characterization of the OLEDs showed a decrease in threshold voltage (from 5.7 to 3.53 v), a decrease in resistance, and an increase in irradiance intensity due to plasma treatment.

Effect of Oxygen Plasma on Polymer Nanocomposites with Carbon Fillers

Effect of Oxygen Plasma on Polymer Nanocomposites with Carbon Fillers

High-Performance Hexagonal Tellurium Thin-Film Transistor Using Tellurium Oxide as a Crystallization Retarder

This study investigates the effect of oxygen plasma (PO) on the crystalline structure of tellurium (Te) thin films during reactive sputtering. Introduction of oxygen radicals suppresses uncontrolled rapid growth of hexagonal Te crystals, amorphizing the deposited Te thin film. This amorphous phase changes to the hexagonal phase upon alumina encapsulation. A 4-nm-thick Te transistor with a PO of 7% exhibits outstanding device performances, with a field-effect mobility up to 40.8 cm2V−1s−1 and an on/off current modulation ratio up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times 10^{{6}}$ </tex-math></inline-formula> . These behaviors originate from alleviated random polycrystallinity in the corresponding thin film. However, when PO increases above 7%, amorphization progresses further, and remnant oxygen ions hamper the growth of the hexagonal phase in Te thin film. Consequently, hole transport is degraded. This study suggests tellurium oxide as a crystallization retarder for high-performance p-channel Te transistors.

Effect of Oxygen Plasma on Polymer Nanocomposites with Carbon Fillers

Effect of Oxygen Plasma on Polymer Nanocomposites with Carbon Fillers

Wideband MOEMS for the Calibration of Optical Readout Systems.

The paper proposes a technology based on UV-LIGA process for microoptoelectromechanical systems (MOEMS) manufacturing. We used the original combination of materials and technological steps, in which any of the materials does not enter chemical reactions with each other, while all of them are weakly sensitive to the effects of oxygen plasma. This made it suitable for long-term etching in the oxygen plasma at low discharge power with the complete preservation of the original geometry, including small parts. The micromembranes were formed by thermal evaporation of Al. This simplified the technique compared to the classic UV-LIGA and guaranteed high quality and uniformity of the resulting structure. To demonstrate the complete process, a test MOEMS with electrostatic control was manufactured. On one chip, a set of micromembranes was created with different stiffness from 10 nm/V to 100 nm/V and various working ranges from 100 to 300 nm. All membranes have a flat frequency response without resonant peaks in the frequency range 0–200 kHz. The proposed technology potentially enables the manufacture of wide low-height membranes of complex geometry to create microoptic fiber sensors.

Effect of different types of substrate surface treatments on the graphene device performance

Graphene–substrate interface is very crucial for analyzing graphene device performance. In this article, we have shown how the graphene device performance got affected because of different types of substrate surface treatment techniques used before graphene transfer. For fabrication of graphene devices, monolayer chemical vapor deposition (CVD) graphene was transferred onto SiO2 grown thermally on Si substrate. Forming gas annealed SiO2/Si shows better device performance as compared with as‐grown SiO2 on Si substrate. A further effect of oxygen plasma and argon plasma cleaning of SiO2 surface before graphene transfer was investigated. Forming gas annealing improves the performance and plasma treatment degrade the graphene devices' performance.

Hydrogen Peroxide Detection Using Prussian Blue‐modified 3D Pyrolytic Carbon Microelectrodes

AbstractA highly sensitive amperometric Prussian blue‐based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre‐treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in μM and sub‐μM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 μM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition

Surface Wettability Tuning of Acrylic Resin Photoresist and Its Aging Performance.

Photoresist is the key material in the fabrication of micropatterns or microstructures. Tuning the surface wettability of photoresist film is a critical consideration in its application of microfluidics. In this work, the surface wettability tuning of acrylic resin photoresist by oxygen plasma or ultra-violet/ozone, and its aging performance in different atmospheres, were systematically studied. The chemical and physical characterizations of the surfaces before and after modification show a dramatic decrease in the C–C group and increase in surface roughness for oxygen plasma treatment, while a decrease of the C–C group was found for the UV/ozone treatment. The above difference in the surface tuning mechanism may explain the stronger hydrophilic modification effect of oxygen plasma. In addition, we found an obvious fading of the wettability tuning effect with an environment-related aging speed, which can also be featured by the decrease of the C–C group. This study demonstrates the dominated chemical and physical changes during surface wettability tuning and its aging process, and provides basis for surface tuning and the applications in microfluidics.

An insight into thermal stability and decomposition kinetics of polybenzoxazine plasma treated graphene nanocomposites

This research was targeted to investigate the effect of oxygen plasma treated graphene nanosheets (tGNSs) on the thermal stability of benzoxazine resin and to have a further and deeper mechanistic understanding of thermal decomposition kinetics of such nanocomposites in 0.5, 1 and 3 wt% of tGNS. The samples were prepared as reported in our previous study. The quality of dispersion of tGNSs within benzoxazine was investigated by X-Ray diffraction (XRD) and scanning electron microscopy (SEM) technique. Also, to ensure the complete curing of samples the differential scanning calorimetry (DSC) analysis was performed. Using thermogravimetric analysis (TGA), it was found that the addition of tGNS improved the char yield and thermal stability parameter of benzoxazine nanocomposites and this improvement was more prominent at 1% and higher amount of nanoparticles. Moreover, the first stage of thermal degradation kinetic of benzoxazine was disappeared above 1 wt% of tGNS. The samples were kinetically analyzed through Kissinger, Flynn-Wall-Ozawa and Friedman and Coats-Redfern method. It was revealed that the overall activation energy was enhanced from 168 to 224 kJ mol−1 and 275 to 420 kJ mol−1 for the second and third stage of degradation using 1 and 3 wt% of tGNS.

Deposition and Characterization of RP-ALD SiO2 Thin Films with Different Oxygen Plasma Powers.

In this study, silicon oxide (SiO2) films were deposited by remote plasma atomic layer deposition with Bis(diethylamino)silane (BDEAS) and an oxygen/argon mixture as the precursors. Oxygen plasma powers play a key role in the quality of SiO2 films. Post-annealing was performed in the air at different temperatures for 1 h. The effects of oxygen plasma powers from 1000 W to 3000 W on the properties of the SiO2 thin films were investigated. The experimental results demonstrated that the SiO2 thin film growth per cycle was greatly affected by the O2 plasma power. Atomic force microscope (AFM) and conductive AFM tests show that the surface of the SiO2 thin films, with different O2 plasma powers, is relatively smooth and the films all present favorable insulation properties. The water contact angle (WCA) of the SiO2 thin film deposited at the power of 1500 W is higher than that of other WCAs of SiO2 films deposited at other plasma powers, indicating that it is less hydrophilic. This phenomenon is more likely to be associated with a smaller bonding energy, which is consistent with the result obtained by Fourier transformation infrared spectroscopy. In addition, the influence of post-annealing temperature on the quality of the SiO2 thin films was also investigated. As the annealing temperature increases, the SiO2 thin film becomes denser, leading to a higher refractive index and a lower etch rate.

Evaluation of the Mechanical Properties of ZnO Nanorods Treated with Oxygen Plasma using Atomic Force Microscopy

Zinc oxide (ZnO) simultaneously exhibits semiconducting and piezoelectric properties. ZnO in the form of nanorods has been studied intensively for application in self-powering devices. The power generation in piezoelectric nanogenerators based on ZnO nanorods can be improved via several approaches, including an oxygen plasma treatment. When ZnO nanorods are exposed to oxygen plasma, the charge carrier concentration decreases and the piezoelectric output voltage consequently increases. However, the effects of oxygen plasma on the mechanical properties of ZnO nanorods has not been systematically studied using a precise measurement technique. Given the size of ZnO nanorods, atomic force microscopy (AFM) is a suitable method for manipulating individual ZnO nanorods and measuring their elastic properties. In the present work, we observed the effects of oxygen plasma on the elemental composition and microstructure of ZnO nanorods. First of all, the surface roughness of the ZnO nanorods was analyzed using AFM, revealing that it increased due to the etching effect of the oxygen plasma. From X-ray photoelectron spectroscopy (XPS) measurements, three distinct peaks corresponding to lattice oxygen, oxygen vacancies, and absorbed oxygen on the surface were identified. The XPS analysis results showed that oxygen vacancy defects on the ZnO nanorods were decreased by oxygen plasma treatment. Next, the effects of oxygen plasma on the elastic properties of ZnO nanorods were studied using lateral force microscopy. It was confirmed that the elastic modulus of ZnO nanorods increased due to the reduced number of defects originating from oxygen vacancies.

Does the plasma application time affect the tensile bond strength between PMMA and a silicone-based denture liner?

This study evaluated the effect of oxygen plasma and argon plasma treatments with different application times on tensile bonding of a silicone-based denture liner to polymethylmetacrylate (PMMA). Seven groups (n = 5) were prepared and six of them treated by argon plasma or oxygen plasma with 30s, 60s, and 120s, respectively; one group was left untreated served as control. After processing of denture liner, the specimens were deflasked and stored dry for 24 h, and they were then subjected to tensile bond strength testing. Differences in tensile bond strength values were determined using one-way ANOVA (α = 0.05). Highest tensile bond strengths were observed in the oxygen plasma groups, followed by untreated group and argon plasma groups in turn in order. Tensile bond strenght were increased with time for both type of plasma applications tested. This study suggests that the adhesion between PMMA and denture liner is improved under conditions of oxygen plasma treatment with extended exposure time rather than argon plasma treatment.

Effect of oxygen plasma cleaning on nonswitching pseudo-Bosch etching of high aspect ratio silicon pillars

In dry plasma silicon etching, it is desired to have a high etching rate, a high etching selectivity to mask material, a vertical or controllable sidewall profile, and a smooth sidewall. Since the standard Bosch process (switching between SF6 and C4F8 gases) leads to a wavy/rough sidewall profile, the nonswitching pseudo-Bosch process is developed to give a smooth sidewall needed for nanostructure fabrication. In the process, SF6 and C4F8 gases are introduced to the chamber simultaneously. Here, the authors show that by introducing a periodic oxygen (O2) plasma cleaning step, that is, switching between SF6/C4F8 etching and O2 cleaning, the silicon etching rate can be significantly improved (by up to ∼55%, from 139 to 216 nm/min) without any adverse effect. This is mainly because O2 plasma can remove the fluorocarbon polymer passivation layer at the surface. The etching and cleaning step durations were varied from 5 s to 40 min and from 0 to 60 s, respectively. The fastest etching rates were obtained when the cleaning step takes roughly 10% of the total etching time.

Effect of Oxygen Plasma on Sprout and Root Growth, Surface Morphology and Yield of Garlic.

Depending on the climate, garlic can be planted either in the fall or spring for a harvest in the summer, but spring planting might require the strengthening of the plant by external techniques. We have used low pressure, inductively coupled, radio frequency oxygen plasma for the treatment of peeled garlic cloves of a spring-planted Slovenian autochthonous cultivar. The aim of the study was to assess the effects of plasma treatment on garlic clove shoot and root growth and, ultimately, the yield. The roles of surface chemistry, surface morphology, and water uptake in these effects were also evaluated. The plasma treatment of cloves induced increases in water uptake. The increases were explained by changes in surface morphology that were determined by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Nanostructured epicuticular wax structures appeared at the cuticle surface. The optimal treatment parameters accelerated root growth, but not shoot growth, in a laboratory setting. After growth in the field, the trends indicated that plant height and dried bulb mass increase, but the improvements were not statistically significant.

A New Effect of Oxygen Plasma on Two-Dimensional Field-Effect Transistors: Plasma Induced Ion Gating and Synaptic Behavior**Supported by the National Key Research and Development Program of China under Grant No 2017YFA0305400, the ShanghaiTech University, and the Natural Science Foundation of Shanghai under Grant No 17ZR1443300.

Plasma treatment is a powerful tool to tune the properties of two-dimensional materials. Previous studies have utilized various plasma treatments on two-dimensional materials. We find a new effect of plasma treatment. After controlled oxygen-plasma treatment on field-effect transistors based on two-dimensional SnSe2, the capacitive coupling between the silicon back gate and the channel through the 300nm SiO2 dielectric can be dramatically enhanced by about two orders of magnitude (from 11 nF/cm2 to 880 nF/cm2), reaching good efficiency of ion-liquid gating. At the same time, plasma treated devices show large hysteresis in the gate sweep demonstrating memory behavior. We reveal that this spontaneous ion gating and hysteresis are achieved with the assistance of a thin layer of water film automatically formed on the sample surface with water molecules from the ambient air, due to the change in hydrophilicity of the plasma treated samples. The water film acts as the ion liquid to couple the back gate and the channel. Thanks to the rich carrier dynamics in plasma-treated two-dimensional transistors, synaptic functions are realized to demonstrate short- and long-term memories in a single device. This work provides a new perspective on the effects of plasma treatment and a facile route for realizing neuromorphic devices.

Surface modification effects of fluorine-doped tin dioxide by oxygen plasma ion implantation

SnO2:F (FTO), as a kind of transparent conductive oxide (TCO), exhibits excellent transmittance and conductivity and is widely used as transparency electrodes in solar cells. It’s very important to modifying the surface of FTO for it plays a critical role in CdTe solar cells. In this study, modifying effects of oxygen plasma on FTO was investigated systematically. Oxygen plasma treatment on FTO surface with ion accelerating voltage ranged from 0.4 kV to 1.6 kV has been processed. The O proportion of surface was increased after ion implantation. The Fermi level of surface measurement by XPS valance band spectra was lowered as the ion accelerating voltage increased to 1.2 kV and then raised as accelerating voltage was elevated to 1.6 kV. The work function measured by Kelvin probe force microscopy increased after ion implanting, and it was consistent with the variation of Fermi level. The change of energy band structure of FTO surface mainly originated from the surface composition variation. As FTO conduction was primarily due to oxyanion hole, the carrier was electron and its concentration was reduced while O proportion was elevated at the surface of FTO, as a result, the Fermi level lowered and the work function was enlarged. It was proved that oxygen plasma treatment is an effective method to modulate the energy band structure of the surface as well as other properties of FTO, which provides much more space for interface and surface modification and then photoelectric device performance promotion.

Kinetics and crystal texture improvements on thin germanium layers obtained by aluminium induced crystallization using oxygen plasma

The fabrication of strongly-textured thin crystalline germanium layers on amorphous silica substrates can be achieved by aluminium induced crystallization using the ‘aluminium induced layer exchange’ mechanism. This requires a diffusion barrier, or interlayer, between the Al and Ge layers with a specific chemistry. We investigate here the effect of oxygen plasma on this interlayer as an alternative route to the standard air-exposure process. We find that the plasma treatment strongly slows down the kinetics of the crystallization. This can be compensated by a higher process temperature, after which the defect density becomes similar to that of air-oxidized but with defects of smaller size. This substantially improves the overall texture of the Ge layer and a near complete (111) orientation is obtained.

Effect of oxygen plasma on nanomechanical silicon nitride resonators

Precise control of tensile stress and intrinsic damping is crucial for the optimal design of nanomechanical systems for sensor applications and quantum optomechanics in particular. In this letter, we study the influence of oxygen plasma on the tensile stress and intrinsic damping of nanomechanical silicon nitride resonators. Oxygen plasma treatments are common steps in micro and nanofabrication. We show that oxygen plasma for only a few minutes oxidizes the silicon nitride surface, creating several nanometer thick silicon dioxide layers with a compressive stress of 1.30(16) GPa. Such oxide layers can cause a reduction in the effective tensile stress of a 50 nm thick stoichiometric silicon nitride membrane by almost 50%. Additionally, intrinsic damping linearly increases with the silicon dioxide film thickness. An oxide layer of 1.5 nm grown in just 10 s in a 50 W oxygen plasma almost doubled the intrinsic damping. The oxide surface layer can be efficiently removed in buffered hydrofluoric acid.

Effects of oxygen plasma generated in magnetron sputtering of ruthenium oxide on pentacene thin film transistors

Effects of oxygen plasma generated in a sputtering process for deposition of electrodes on pentacene thin films to configure top-contact (TC) transistors have been thoroughly investigated. Reactive oxygen species severely degraded electrical properties of pentacene films during the deposition of RuOx electrodes, leading to a failure of devices. In the off-region, the leakage current increased by about two orders of magnitude, and the subthreshold slope also increased by 6.5 times. The top surface of pentacene films was oxidized by oxygen plasma and C-O and C=O bonds awerere created. The pentacenequinone derivative was confirmed by X-ray photoelectron spectroscopy. The oxidation of pentacene films gives rise to charge traps at the pentacene/electrode interface, which produces a leakage channel between source and drain electrodes. We believe that this side effect of oxygen plasma on the fabrication of TC-devices should be considered carefully.

Tuning the adhesion between polyimide substrate and MWCNTs/epoxy nanocomposite by surface treatment

MWCNTs/epoxy nanocomposite thin films are coated on the polyimide (PI) flexible substrate, to be used as a strain sensor. Previous studies showed that the adhesion between polyimide and other materials are very poor. In this work, two approaches, oxygen plasma cleaning and simple solvent cleaning are performed for activation of the polyimide surface. In order to understand the impact of both cleaning techniques, the physicochemical properties of PI are measured and characterized using contact angle measurements (CAMs), X-ray photoelectron spectroscopy(XPS), and atomic force microscopy (AFM). In addition, the adhesion properties of PI/[MWCNTs/epoxy] systems by varying surface treatment time are investigated and evaluated using force–distance measurements by AFM. The results illustrate that the activated surface exhibits higher surface energy for oxygen plasma cleaning in comparison with the solvent cleaning method. The improvement can be related to the increase of oxygen concentration, which is accompanied by the enhancement of the polar component to 53.79mN/m due to the formation of functional groups on the surface and the change of the substrate surface roughness from 1.72nm to 15.5nm. As a result, improved adhesion was observed from force–distance measurement between PI/[MWCNTs/epoxy] systems due to oxygen plasma effects.