Effect Of Oxygen Plasma Treatment Research Articles

氧等离子体处理对GaAs表面单层自组装SiO2纳米球薄膜的影响

氧等离子体处理对GaAs表面单层自组装SiO2纳米球薄膜的影响

The effect of oxygen plasma treatment of gold electrodes on the molecular orientation of CuPc films

Gold (Au) is a commonly used material for many organic electronic device electrodes due to its chemical stability and high work function, which is required for p-type semiconductors. The orientation and morphology of organic semiconductors deposited on such electrodes often depends crucially on the cleanliness of the Au surface. In this study, we examine the effect of a common cleaning method, namely oxygen plasma cleaning, on sputter-deposited polycrystalline Au electrodes and subsequently deposited copper-(II)-phthalocyanine (CuPc) films. Using X-ray diffraction (XRD), atomic force microscopy (AFM) and near-edge X-ray absorption fine structure (NEXAFS) measurements, we show that the metastable Au oxide typically formed during an oxygen plasma cleaning process significantly impacts the molecular orientation and morphology in CuPc thin films, forcing molecules to adopt an upright orientation. We further demonstrate that the typical recumbent orientation of CuPc adopted on clean polycrystalline Au can be achieved by an additional annealing step after oxygen plasma treatment of the Au electrode that causes a decomposition of the gold oxide.

Spectroscopic Analyses of Sputtered Aluminum Oxide Films with Oxygen Plasma Treatments

X-ray photoelectron spectroscopy (XPS) and Spectroscopic Ellipsometry (SE) were used to analyse the effect of oxygen plasma treatment on properties of aluminum oxide thin films. The aluminum oxide films were fabricated using a reactive sputtering system. The as-deposited films were treated with oxygen plasma powered by an RF generator. During the plasma treatment, the pressures were set at 1 x 10-1 to 1x 10-2 mbar, while the RF supplied powers at 100 W and 200 W. It was observed that lower plasma powers and higher pressures resulted in smoother films. The O/Al ratio of the films were found to decrease with increasing plasma powers and pressures. The thickness and refractive index of the films were significantly affected by the oxygen plasma treatment process, which could be related to the change in films’ packing density and the etching at the surface.

Effect of oxygen plasma treatment on bonding strength of epoxy coating on steel substrate

In this work, the surface of Q235 steel was pretreated by low-temperature atmospheric pressure oxygen plasma in order to improve the bonding strength between the epoxy coating and the metal substrate. The epoxy coating was prepared by electrostatic spraying. The bonding strength between the epoxy coating and the Q235 steel was characterized by a coating peeling experiment. XRD, laser scanning microscope were employed in this research to characterize the chemical and physical properties of the Q235 surface before and after treatment. The experimental results showed that oxidize occurred on the surface of the Q235 steel after oxygen plasma pretreatment, which improved the surface roughness and free energy. Meanwhile, polar groups were introduced on the steel surface. With the increase in treatment time, the bonding strength increased first and then decreased. When the treatment time was 2 min, the bonding strength reached the highest (7.51 MPa), which was an increase of 3.5 times compared with the untreated sample (1.67 ± 0.48 MPa).

The effect of oxygen plasma treatment on the field emission properties of lanthanum hexaboride tip emitter

Polycrystal lanthanum hexaboride (LaB6) tip field emitter has been prepared using the electrochemical etching technique. The effects of oxygen plasma treatment on its morphology, structure and field emission properties are mainly discussed. The results reveal that the surface morphology of emitters did not change significantly after oxygen plasma treatment. The oxygen plasma treatment does not introduce any new phase into LaB6 emitter, but eliminates surface contaminants, which lead to lower work function. The cathode treated by 2 min shows the best emission performance during the field emission measurement. It obtains 8.2 μA at 2000 V, especially exhibiting strong ability of anti oxygen ion bombardment.

Effect of Inductively Couple Plasma‐Based Oxygen Plasma Treatment on AlGaN/GaN HEMT

In this paper, the physical mechanism and trap effect of AlGaN/GaN high electron mobility transistor HEMT with inductively couple plasma (ICP) based oxygen plasma treatment are investigated. Three devices with different oxygen plasma treatment conditions are fabricated and compared to a conventional device. To understand the physical mechanism of oxygen plasma treatment by ICP, the chemical composition change of the barrier layer is studied through X‐ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM), and the Al molar composition changes of the barrier layer after oxygen plasma treatment are numerically calculated. By numerical calculation of the polarization effect, it is found that an increase in time and RF power of the ICP increase the oxidation effect while the etching effect is decreased. Meanwhile, the trap effect of the devices that has treated with oxygen plasma treatment is also studied. In this study, the authors found that the greater the RF power is, the great the number of deep‐level trap states introduced by oxygen plasma treatment. However, the effect of oxygen plasma treatment on trap states is relatively limited, indicating that the trap density introduced by the ICP‐based oxygen plasma treatment is low.

Effect of Oxygen Plasma Treatment on Film Structure for Different Types of DLC film

Effect of Oxygen Plasma Treatment on Film Structure for Different Types of DLC film

Low-cost scalable printing of carbon nanotube electrodes on elastomeric substrates: Towards the industrial production of EAP transducers

Dielectric elastomer transducers are promising devices for a growing field of applications. However, to be competitive with established electromechanical transducer technologies, low-cost and efficient fabrication process is needed. In particular, the electrode composition and deposition method seem to be the key elements in this context. In this paper, authors use gravure printing for the deposition of thin and compliant MWCNT electrodes on PDMS films. Gravure printing is a high through put deposition method which allows printing complex electrode patterns whit high resolution and, therefore, is well suited for large scale production of dielectric elastomer transducers. Special attention was given to the adaptation of the MWCNT-based ink to the specific requirements of the gravure printing process in order to achieve stable and high quality printing. Furthermore, the effect of oxygen plasma treatment of the silicone substrate on the electro-mechanical behavior of electrode was investigated. In this context a comprehensive characterization of the electrodes behavior under uniaxial and biaxial strain was carried out. Two mechanisms that explain specific aspects of electro-mechanical behavior of electrodes are proposed.

Insight into the modification of electrodonor properties of multiwalled carbon nanotubes via oxygen plasma: Surface functionalization versus amorphization

The effect of oxygen plasma treatment on multi-walled carbon nanotubes (MWCNTs) surfaces towards controlled tuning of their electrodonor properties (gauged by the work function) was investigated experimentally (X-ray diffraction, Raman spectroscopy, thermogravimetry, transmission electron microscopy, X-ray photoelectron spectroscopy) and by molecular modeling (Density Functional Theory). The nanotubes were treated with oxygen plasma (0.2 mbar) at varied generator power (20–60 W) and exposure time (0.1–30 min). It was found that the work function changes nonmonotonously upon plasma treatment: after significant increase (from 4.5 eV to 5.9 eV) and passing through maximum the work function decreases and finally reaches a plateau. The experimental results supported by DFT calculations allowed to propose a molecular model explaining the changes in carbon nanotube surface induced by oxygen plasma. Two different oxygen adatom locations: out-of-plane (Csurf–Oadatom) and in-plane (Csurf–Osurf–Csurf) were identified, leading to formation of surface dipoles (formation of negative potential barrier, work function increase) and incorporation of oxygen into the carbon structure (cancellation of the potential barrier, work function decrease), respectively. The critical regions of plasma parameters for oxygen surface decoration and amorphization were identified providing guidelines for rational designing and tuning of MWCNT electrodonor properties.

Effect of Oxygen Plasma Treatment on Fabrication of Bioactive Ultrahigh Molecular Weight Polyethylene Composite

Effect of Oxygen Plasma Treatment on Fabrication of Bioactive Ultrahigh Molecular Weight Polyethylene Composite

Effects of oxygen plasma treatment on domestic aramid fiber III reinforced bismaleimide composite interfacial properties

Domestic Aramid Fiber III (DAF III) was modified by oxygen plasma treatment. The fiber surface characteristics was observed by Scanning Electron Microscopy. The results showed that oxygen plasma treatment changed surface morphologies. The effects of oxygen plasma treatment on DAF III reinforced bismaleimides (BMI) composite bending and interfacial properties were investigated, respectively. The ILSS value increased from 49.3 MPa to 56.0 MPa (by 13.5%) after oxygen plasma treatment. The bending strength changed a little. Furthermore, the composite rupture mode changed from interfacial rupture to fiber or resin bulk rupture.

Effect of oxygen plasma treatment and gold sputtering on morphological and local mechanical properties of copolyimide/gold micropatterned structures

Atomic force microscopy (AFM) was used to analyze rectangular 3‐dimensional patterned microstructures with different functionalities induced on copolyimide containing alicyclic sequences film surfaces by means of oxygen plasma treatment. The plasma power was ranged to be big enough to accelerate the plasma species towards the copolyimide surface, and the exposure time was not very small to generate a roughness that still can be monitored by AFM. To create the rectangular pattern, transmission electron microscopy grid masks were placed on the samples before treatment. Plasma‐induced micropatterning with alternating hydrophilic and hydrophobic surface chemistries was evaluated by measuring the adhesion forces between the gold‐covered AFM tip and the copolyimide surfaces. To fabricate 3‐dimensional metallic microstructures arranged in well‐defined areas, thin metal layers were sputtered on these pretreated copolyimide films. The AFM morphological aspects of the obtained metallic structures were correlated with the surface modifications induced by plasma treatment conditions. Functional indexes and functional volume parameters were also calculate to characterize the functional behavior of the surface, such as wear, lubrication, and contact. The AFM data were compared with those obtained using the small‐angle X‐ray scattering measurements.

Improved Schottky barrier characteristics for AlInN/GaN diodes by oxygen plasma treatment

In this work, the effects of oxygen plasma treatment by inductive coupled plasma on current transport of AlInN/GaN Schottky diodes were investigated. The current-voltage (I-V) results show that oxygen plasma treatment can significantly suppress reverse leakage current of the Schottky diodes by over three orders of magnitude, and meanwhile can enhance remarkably the effective barrier height and improve the ideality factor of the Schottky contact by forming a thin oxidation layer at the AlInN surface. However, I-V curve occurs a transient and recoverable reduction in current response at low forward bias. The further analysis indicates that donor-like traps related to nitrogen vacancies or their complexes induced by oxygen plasma treatment are responsible for this transient current reduction.

Effect of Oxygen Plasma Treatment on Wicking behavior of Bamboo Nonwoven Fabric

Effect of Oxygen Plasma Treatment on Wicking behavior of Bamboo Nonwoven Fabric

Effect of oxygen plasma treatment on tensile strength of date palm fibers and their interfacial adhesion with epoxy matrix

Abstract In recent years, natural fibers have received much attention from various industrial applications. As these fibers are lightweight, nonabrasive, low cost, ecofriendly and biodegradable, they can be sometimes considered as alternatives to synthetic fibers in lightweight composite structures. In this work, date palm fibers (DPFs) were treated by oxygen plasma at various plasma discharge power and exposure time. The effects of plasma treatment on tensile strength of DPF and interfacial adhesion between DPF and epoxy were determined by single fiber tensile test and microbond test, respectively. Scanning electron microscopy was used to investigate the surface morphologies of DPFs before and after the plasma treatment. The functional groups on the surface were studied by attenuated total reflectance-Fourier transform infrared spectroscope (ATR-FTIR). Decrease in hemicellulose and lignin content of DPF was indicated in ATR-FTIR spectra of the treated sample with plasma treatment. The results show that plasma treatment cleans the fiber surface and increases the surface roughness by etching effect. Moreover, fiber surface modification significantly improves tensile properties of DPFs and interfacial shear stress (IFSS) of fiber/matrix. However, the effects of plasma power and exposure time on tensile properties and IFSS values of DPFs are not found significant. Moreover, Weibull statistics show that plasma treatment could not decrease the variability in fiber strength due to the nature of fibers.

Adhesion of NCF to oxidized Si wafers after oxygen plasma treatment

The effect of oxygen plasma treatment on the adhesion between nonconductive film (NCF) and oxidized Si was investigated. Oxidized Si wafers were treated with oxygen plasma for 5min and then rinsed in de-ionized water (DIW). The water contact angle was measured by means of the sessile drop technique and the surface roughness was measured by means of atomic force microscopy. The adhesion of the NCF to the oxidized Si wafer was evaluated by means of a single-lap shear test after bonding at 150°C for 5 s. Oxygen plasma treatment decreased the water contact angle. The roughness of the oxidized Si wafer decreased when oxygen plasma treatment was applied alone, but was increased when both oxygen plasma treatment and DIW rinse were applied. Similarly, the shear strength decreased when oxygen plasma treatment was applied alone, but the adhesion of NCF increased when both oxygen plasma treatment and DIW rinse were applied. The increased surface roughness of the oxidized Si wafer played an important role in increasing the adhesion between the NCF and the oxidized Si wafer. The shear strength further increased after post-heat treatment at 170°C for 1 hr or at 280°C for 15 s. Low shear strength observed before post-heat treatment was ascribed to incomplete NCF curing. Differences observed in the adhesion strength between two types of NCF were attributed to differences in their curing degrees and their degrees of surface coverage of the oxidized Si substrates.

Effect of oxygen plasma treatment on performance of ZnO based dye sensitized solar cells

In this paper we present impact of oxygen (O2) plasma treatment on zinc oxide (ZnO) films and the optimization of their performance as photoanodes in dye sensitized solar cells (DSSCs) employing the I−/I3− electrolyte and the N719 sensitizer. Detailed surface and structural characterization of the ZnO films were accomplished using XRD and scanning electron microscopy (SEM) analysis. XRD results revealed the synthesized ZnO material to be highly crystalline and exhibit hexagonal crystal structure. The surface morphology suggested the grains to appear in spherical shape and distributed randomly. The ZnO based DSSC without treatment of O2 plasma showed the short-circuit photocurrent density (Jsc) 0.40 mAcm−2, open-circuit voltage (Voc), 0.50 V and fill factor (FF) 0.47 and power conversion efficiency of 0.36%. After 15 min of O2 plasma treatment ZnO based DSSCs exhibited short-circuit photocurrent density (Jsc) 1.10 mAcm−2, open-circuit voltage (Voc), 0.42 V and fill factor (FF) 0.43 and enhanced power conversion efficiency of 0.76%.

Surface Functionalization of WO3 Thin Films with (3-Aminopropyl)triethoxysilane and Succinic Anhydride

We report effects of oxygen plasma treatment on the surface functionalization of WO3 thin films with (3-aminopropyl)triethoxysilane (APTES) and succinic anhydride (SA). X-ray diffraction and x-ray photoelectron spectroscopy results indicate the existence of the WO3 phase. Fourier transform infrared spectroscopy measurement shows clear bands at 1040 cm−1 (Si–O–Si), 1556 cm−1 (N–H), 1655 cm−1 (C=O), 2937 cm−1 (C–H) and 3298 cm−1 (N–H), confirming the surface functionalization efficiency enhanced by prior treatment of oxygen plasma. It thus follows that the prior oxygen plasma treatment activates hydroxylation with more –OH groups on the WO3 surface, which can pave a highly efficient way to the surface functionalization by APTES and SA.

Effects of oxygen-plasma treatment on the structure and optical properties of MgxZn1−xO films

A MgxZn1−xO film was grown on a sapphire substrate using a radio-frequency magnetron sputtering system and then subjected to oxygen-plasma treatment. The effects of the treatment time on the structural, optical photoluminescence (PL), and chemical state properties of the MgxZn1−xO films were studied. It was found that the crystal quality improved with treatment time because a longer oxygen-plasma treatment provided more energy to improve the crystal quality. The bandgap increased slightly from 3.654eV for the as-deposited film to 3.660eV for 15-min-treated film. The increase in the bandgap was attributed to a decrease in the tensile strain of the film; a linear relationship between the bandgap and the strain was also observed. PL spectra showed that the ultraviolet intensity increased with the treatment time, and the defect emission decreased as the treatment time increased up to 10min. When the treatment time exceeded 10min (i.e., for the 15-min-treated film), the defect emission increased significantly. X-ray photoelectron spectroscopy demonstrated that the Mg–O bonding increased from 66% for the as-deposited film to 87% for the 10-min-treated film; however, the Mg–O bonding showed a slight reduction in the 15-min-treated MgxZn1−xO film owing to the longer plasma treatment time. The relevant mechanisms were studied.

Channel Modification Engineering by Plasma Processing in Tin-Oxide Thin Film Transistor: Experimental Results and First-Principles Calculation

In this paper, we investigated the effects of oxygen plasma treatment on tin oxide (SnOx) thin film transistors (TFTs). By using oxygen plasma treatment on SnOx active channel layer, excess oxygen was incorporated to the channel layer and converted oxygen-deficient SnOx to oxygen-rich SnO2-x, which in turn causes the device operation from p-type to n-type. Tuning the different exposure time of oxygen plasma, the optimal TFT device exhibits n-type properties with an on/off current ratio of 2.6 × 104, a very high field-effect mobility of 89 cm2 V−1 s−1, and a threshold voltage of −0.95 V. Furthermore, the effects of oxygen plasma treatment on band structure, density of states and electron density difference of the SnOx channel layer were performed by the first-principles calculation using density functional theory. The results show that the oxygen plasma treatment approach has high potential for high-performance TFT applications.