Influence Of RF Power Research Articles

Influence of RF Power on Wettability, Morphology and Bacterial Adhesion Properties of Oxygen Plasma Treated Silicone Catheter Surfaces

Influence of RF Power on Wettability, Morphology and Bacterial Adhesion Properties of Oxygen Plasma Treated Silicone Catheter Surfaces

Influence of deposition power and annealing on the performance of RF-sputtered SnS for infrared photodetection

Tin sulfide has shown their great potential in electronic and photonic systems due to its unique optoelectronic properties, less toxic nature, cost-effective and economically earth-abundant elements. The multivalence of Sn and stereochemical activity endow it with rich phase spaces and susceptible internal structures, which in turn directly affect its properties. In this paper, optimization studies towards the influence of RF power and post-deposition annealing temperature on the micro structure and photodetection performance of SnS are achieved by RF magnetron sputtering method. The structural characterizations confirm the significance of RF power for phase formation and photoelectric conversion ability. The optical band gap shifts from 1.41 eV to 1.30 eV as RF power increasing from 30 W to 50 W, in the meantime, the optoelectronic performances such as responsivity and specific detectivity are subsequently improved to be 226.55 mA/W and 1.76 × 1010 Jones. Further, the variations in infrared photodetection performance correlated with the annealing temperature exhibite a more well-behaved photoresponse at 300 °C. The results pave the way to discern the growth − structure − property relationships and then guide potencial applications of tin sulfide family.

Transition between monoclinic and tetragonal β phases induced by reactive oxygen gas in RF-sputtered V2O5 thin films

Thin films of V2O5 are promising materials for applications in chromogenic devices, such as gas sensors and contactless optical thermal sensors. Therefore, controlling the formation of the various phases of V2O5 is important. The device performance, in relation to satisfactory coloration efficiency and fast response, strongly depends on the characteristics of the phase incorporated in the film structure. To better understand the phase formation in these films, thin films of V2O5 were deposited by RF magnetron sputtering using an O2-reaction technique from a metallic V target, and the influence of RF power and O2 levels on the transition between the β-monoclinic and β-tetragonal phase structures was investigated by X-ray diffractometer. The films were also evaluated using Auger-electron, Raman-, and UV-vis spectrometers to determine their composition, chemical, and electronic properties to assess the effects of the two sputtering parameters. The mechanism underlying the development of film properties is related to the plasma characteristics and species observed by optical emission spectroscopy. Increasing the RF power resulted in a higher phase content of the β-monoclinic and α-orthorhombic phase, whereas an increasing the oxygen levels induced a phase transition towards the β-tetragonal phase of V2O5. Films with different phase contents exhibited different optical energy bandgaps. Plasma diagnostics showed that increasing the RF power increased the thickness of plasma sheaths on the target surface. The thinner sheath on the target surface further increased the β-tetragonal phase content. The variation between β-monoclinic and β-tetragonal phase content was expected because of the bombardment of energetic O− ions that were accelerated from the plasma sheath toward the growth surface. A deeper understanding of the transition between β phases in V2O5 films can enable better phase control, which can improve film application towards various sensing devices, particularly chromic- or temperature-sensors.

Investigating optical, structural and morphological properties of polycrystalline CdTe thin-film deposited by RF magnetron sputtering

In this work, optimization of the physical properties of cadmium telluride (CdTe) thin films has been carried out to improve its performance by the influence of RF power. CdTe Nanocrystalline thin films were characterized by using various techniques such as atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). XRD study revealed that CdTe films are polycrystalline and have preferential growth in (111) direction. FESEM images showed a continuous and dense morphology of CdTe films on glass substrates. The AFM result shows that the surface roughness of films increases with annealing. Optical properties were investigated with the help of the UV–visible absorption spectrum which showed that the bandgap decreases with an increase in Radio-frequency power. Further, density functional theory (DFT) calculations showed that the optimum bandgap i.e. 1.57 eV for CdTe films deposited at 100 W RF power with 2% N2 is in good agreement with the experimental result. This study showed that CdTe films deposited at 100 W RF power with 2% N2 can be used as an excellent absorbing material for the application of optoelectronic devices solar cells.

Influence of RF-power on the optical, structural, and morphological properties of ZnS:Cr thin films

ABSTRACT In this work, the morphological, optical, and structural properties of ZnS:Cr films deposited by RF-sputtering are examined for different RF-powers. For this, thin films (ZnS) and (ZnS:Cr) were deposited on glass and Si substrates. The deposition time was set at 90 min, and the RF power varied in the range of 100–200 W. X-ray indicated that all the ZnS films were single-phase with apreferred growth orientation along the (111) plane of the (ZB) phase. The Cr-doped ZnS, and showed the (111) (2 20) and (311) peaks of the same phase. The ZnS films showed acrystallite size of 25.45 nm for RF power of 200 W. While in the case of ZnS:Cr, the crystallite size increased from 16.6 nm to 28.5 nm. The strain was shown to decrease from 2.2 × 10−3 to 1.45 × 10−3. SEM observations revealed smooth film surfaces. (EDS) revealed that the Cr rate is smaller than the Zn and Srates. UV- measurements revealed that the ZnS films exhibit an average transmittance on the order of 70% whilst that the ZnS:Cr was less than 60% in the visible wavelength region. Moreover, the optical bandgap of the ZnS films was found to be equal to 3.57 eV, and decreases for ZnS:Cr.

Morphological Control in Gold Nanostructures Synthesis Process

Noble metal nanoparticles (NPs) have unique optical, electronic and catalytic properties. Dome-like gold (Au) NPs having a size as small as [Formula: see text][Formula: see text]nm and a high density of [Formula: see text][Formula: see text]cm[Formula: see text] were prepared by very high frequency (VHF) hydrogen (H[Formula: see text] plasma-assisted radio frequency magnetron sputtering (RFMS) technique. The influence of RF power and sputtering time on the morphology and structure of islands-like Au nanostructures (NSs) were determined. Besides, optimum sputtering sample (OSS) was treated by VHF H2 plasma technique to fabricate dense Au NPs with great uniformity. Prepared samples were studied by atomic force microscope (AFM), energy dispersive X-ray spectroscopy (EDX) and high-resolution transmission electron microscope (HR-TEM). AFM images of the sputtering samples show a good density of islands-like Au NSs ([Formula: see text][Formula: see text]cm[Formula: see text] with relatively homogeneous distribution. VHF H2 plasma treatment dependent alterations in the surface morphology of the OSS (shape, size, distribution, number density and average surface roughness) were clearly manifested in the AFM images. EDX spectra disclosed prominent Au peaks highly sensitive to the H2 plasma treatment. Our novel fabrication method may contribute to the development of Au NPs based nanodevices.

Influence of rf power on growth, structural and optical properties of ZnO synthesized via vapor transport in inductively coupled plasma

The aim of this work was to examine the influence of radio frequency (rf) power on ZnO films synthesized by means of chemical vapor transport technique in inductively coupled plasma (ICP). As the rf power increased, with a fixed processing time of only 8 min, the temperature inside the reactor tube, the thickness and surface roughness of the formed polycrystalline ZnO films increased. The morphology of the ZnO films changed to oblate, webby like cloud-grains, nanoslices, and a mixture of nanorods and nanograins with changing the rf power from 300 to 500 W. Mixed phases of hexagonal ZnO and hexagonal Zn were found for samples synthesized at 300 and 500 W whereas single hexagonal ZnO was synthesized at 350, 400 and 450 W. The optical band gap decreased from 3.35 eV to 3.05 eV with increasing the rf power from 300 W to 500 W. The refractive index and extinction coefficient values were mainly increased with increasing the rf power. The electrical resistivity was generally decreased with increasing rf power and has values between 1.38 × 10−2 - 2.83 × 10−3 Ωcm. The obtained results might be important for useful applications of ZnO films grown by chemical vapor transport with the assistance of ICP.

Influence of RF power and CH4 flow rate on properties of diamond-like carbon films deposited by PECVD technique

In this work, Diamond like carbon (DLC) films were deposited on titanium substrate by plasma enhanced chemical vapor deposition (PECVD) technique. The influences of RF power and CH4 gas flow rate on the properties of the DLC films were studied using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and synchrotron-based near-edge X-ray absorption find structure (NEXAFS) spectroscopy. The results show that the sp3/sp2 ratio decreases, while the ID/IG increases when RF power increases. The sp3/sp2 ratio increases with CH4 flow rate.

Influence of the target power on the microstructure and electrical properties of Al-doped ZnO thin films deposited at room temperature

The columnar structure and its formation process have a significant effect on the electrical properties of Al-doped ZnO (AZO) thin film in-situ deposited at room temperature by magnetron sputtering method. The influences of RF power on the formation of the columnar structure and its regular pattern were systematically investigated. The RF power varied from 120 W to 240 W. The best quality AZO sample with the sheet resistance of 6.07 Ω/sq and average transmittance of 83.2% was obtained at 210 W (for 30 min). The analysis of crosses section images indicated that the columnar structure appeared earlier at higher RF power. The thickness at which the columnar structure began to appear didn't fluctuate at a fixed value. Furthermore, high RF power relatively contributed to reduce the thickness. The Drude's model was used for examining the correlation between optical and electrical behaviors, and the theoretical results of electrical properties were well matched with the experimental data. According to the XRD results and XPS analysis, the appearance of Al2O3 may exert a significant influence on the deterioration in electrical properties of the sample deposited at 240 W.

Analysis of the effect of sputter power on the morphological and mechanical characteristics of titanium thin films deposited on high-speed steel (HSS)

High speed steel or HSS is a material class of tool steels which could withstand high temperatures without losing their hardness, and are highly resistant to abrasions which allows them to cut other materials faster compared to other carbon & tool steels. As a result, these materials are extensively used in the manufacturing of various cutting tools utilized in mechanical laboratories and industries. Herein, we deposited titanium thin-film on a high-speed steel (HSS) substrate using radio frequency (R.F) magnetron sputtering. We varied the RF power while other parameters were kept constant. The microstructure analyses of these HSS coated with Ti-films illustrated variations in the particle size and morphology with varying power. The influence of RF power was also observed on the surface hardness of the Ti-coated HSS. The hardness of the samples showed an improvement with increasing applied R.F power. Thus, an interplay of RF sputter power on the microstructure and mechanical hardness was systematically observed and analyzed.

Role of RF power on physical properties of RF magnetron sputtered GaN/p-Si(1 0 0) thin film

Abstract GaN thin films were deposited on p-Si(1 0 0) substrates using RF magnetron sputtering at various RF powers. Influence of RF power on morphological, optical and structural properties of GaN thin films were investigated and presented in detail. XRD results proved that the films were polycrystalline in structure with (1 0 0) and (1 1 0) planes of hexagonal GaN. It was found that increasing RF power led to deterioration of crystal structure of the films due to increased decomposition of GaN. Stress in GaN thin films was calculated from XRD measurements and the reasons for this stress were discussed. Furthermore, it was analyzed and interpreted whether the experimental measurement results support each other. E2 (high) optical phonon mode of hexagonal GaN was obtained from the analysis of Raman results. UV-Vis spectroscopy results showed that optical band gap of the films varied by changing RF power. The reasons of this variation were discussed. AFM study of the surfaces of the GaN thin films showed that some of them were grown in Stranski-Krastanov mode and others were grown in Frank-Van der Merwe mode. AFM measurements revealed almost homogeneous, nanostructured, low-roughness surface of the GaN thin films. SEM analysis evidenced agglomerations in some regions of surface of the films and their possible causes have been discussed. It has been inferred that morphological, optical, structural properties of GaN thin film can be changed by controlling RF power, making them a potential candidate for LED, solar cell, diode applications.

Influence of RF power on the stoichiometry, optical, and electrical properties of chromium oxide coatings prepared by reactive magnetron sputtering

An investigation has been carried out on the stoichiometry, optical and electrical properties of chromium oxide thin films prepared under various deposition powers using RF magnetron sputtering technique. The elemental and chemical composition of the prepared films were characterised by energy dispersive x-ray (EDX) analysis, Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The wettability and surface energies of the thin films were investigated with a goniometer. The four-point electrical probe method was used to determine the electrical resistivity of the films while the optical properties of the films were measured with a spectrophotometer. The coatings were found to be mainly phase based on the dominance of A1g and Eg symmetric modes in the Raman investigations and the Eu vibration mode in the FTIR measurements. The RF powers used during the deposition process were found to have played a vital role in the formation of rich films. It was observed that higher deposition power facilitated both the dislodging of more chromium atoms from the target and dissociation of oxygen used during the deposition process. The wettability results show that the thin films are hydrophilic and interact well with water and this behaviour is linked to the contribution of the polar component to the total surface energy. Optical transmittance values exceeding 70% were obtained for the films prepared at a lower RF power. The resistivity values varied from 0.061 Ω cm to 0.152 Ω cm for the deposited chromium oxide films. The variation in the electrical resistivity and the optical transmittance of the films with RF power indicate that these film properties can be altered or tuned to suit specific applications e.g. as transparent conducting oxide (TCO) for optoelectronic devices and other similar applications.

Nb and Ta Co-Doped TiO2 Transparent Conductive Thin Films by Magnetron Sputtering: Fabrication, Structure, and Characteristics

Nb and Ta co-doped anatase titanium dioxide (NTTO) nanocrystalline thin films were deposited on quartz and Si (100) substrates by RF magnetron sputtering. The influence of RF power on the growth, structure, morphology, and properties of the samples are discussed in detail. X-ray diffraction measurements show that the films are polycrystalline with anatase tetragonal structure, which is further confirmed by Raman spectroscopy analysis. Meanwhile, Raman spectroscopy results indicate that the peak width of Eg(1) mode, which is directly correlated to the carrier density, changes obviously with RF power. It is found that the substitution of Nb5+ and Ta5+ at Ti site is significantly improved with the increase of RF power from 150 W to 210 W. For the sample deposited at 210 W, the optical transmittance is above 82% in the visible range and the electrical resistivity is as low as 1.3 × 10−3 Ω cm with carrier density of 1.1 × 1021 cm−3 and Hall mobility of 4.5 cm2 V−1 s−1. The optical and electrical properties of NTTO thin films can be compared to those of Nb or Ta doped anatase TiO2. However, co-doping with Nb and Ta gives a possible platform to complement the limitations of each individual dopant.

Influence of RF power on the opto-electrical and structural properties of gallium-doped zinc oxide thin films

GZO thin films were succesfully deposited onto n-Si and glass substrates by RF magnetron sputtering at room temperature. The structural, morphological and opto-electrical properties of the films were investigated in terms of RF power, using various methods such as XRD, AFM, SEM, EDX, XPS, SIMS, UV–Vis–NIR spectroscopy and Hall effect measurements. The achieved results revealed that the all films have highly c-axis (002) oriented polycrystalline structure with high transmittance in Vis and high reflectance in NIR region as well as good conductivity. Meanwhile, surface of the films was uniform, compact and crack-free. With incerasing of RF power, it was seen that crystallinity of the films improved and the grain size became larger. It was also observed that optical band gap of the films was increased to the order of 0.15 eV as well as decreasing the resistivity to the order of 6.38 Ω cm with increasing RF power from 100 to 200 W. Deposited film at 200 W, which can be optimum sputtering power for coating GZO films, having high concentration of free electrons and lowest resistivity exhibited the highest IR reflectivity (~55%) in NIR region. In addition, deposited GZO films at this power have larger particle size and highly optical transmittance (~87%) in visible region. Obtained both of optical and electrical results suggested that the deposited GZO films can be used in low thermal emissivity coating for energy efficient glass and the UV-blocking layer as well as transparent conductive oxide electrode for flexible opto-electronic devices.

Influence of RF power on structural optical and electrical properties of hydrogenated nano-crystalline silicon (nc-Si:H) thin films deposited by PE-CVD

We report synthesis of hydrogenated nanocrystalline silicon (nc-Si:H) thin films by using conventional plasma enhanced chemical vapor deposition (PE-CVD) system from gas mixture of pure silane (SiH4) and hydrogen (H2). We investigated the effect of RF power on structural, optical and electrical properties using various characterization techniques including Raman spectroscopy, FTIR spectroscopy, UV–visible spectroscopy etc. Low angle XRD and Raman spectroscopy analysis revealed that the RF power in PE-CVD is a critical process parameter to induce nanocrystallization in Si:H films. The FTIR spectroscopy analysis results indicate that with increase in RF power the predominant hydrogen bonding in films shifts from Si–H to Si–H2 and (Si–H2)n bonded species bonded species. However, the bonded hydrogen content didn’t show particular trend with change in RF power. The UV–visible spectroscopy analysis shows that the band tail width (E04–ETauc) with increase in RF power. The defect density and Urbach energy also increases with increase in RF power. The highest dark conductivity (and lowest charge carrier activation energy) was obtained for the film deposited at RF power of 125 W indicating that 125 W is optimized RF power of our PE-CVD unit. At this optimized RF power nc-Si:H films with crystallite size ~3.7 nm having good degree of crystallinity (~86.7 %) and high band gap (ETauc ~ 2.01 eV and E04 ~ 2.58 eV) were obtained with a low hydrogen content (6.2 at.%) at moderately high deposition rate (0.24 nm/s).

Properties of ZnO:Ga thin films deposited by RF magnetron sputtering under various RF power

ZnO:Ga thin films were deposited by RF magnetron sputtering technique from ZnO (3 wt.% ) target onto glass substrates under various RF power. The influence of RF power on the structural, electrical, and optical properties of ZnO:Ga thin films was investigated by X-ray diffraction, atomic force microscopy, Hall method and optical transmission spectroscopy. As the RF power increases from 50 to 110W, the crystallinity is deteriorated, the root main square surface roughness is decreased and the sheet resistance is increased. The increase of sheet resistance is caused by decreasing carrier concentration due to interstitial Ga ion. All films are transparent up to 80% in the visible wavelength range and the adsorption edge is a red-shift with increasing RF power.

Influence of RF power on structural, morphology, electrical, composition and optical properties of Al-doped ZnO films deposited by RF magnetron sputtering

In this study, influence of RF power on the structural, morphology, electrical, composition and optical properties of Al-doped ZnO (ZnO:Al) films deposited by RF magnetron sputtering have been investigated. Films were systematically and carefully investigated by using variety of characterization techniques such as low angle X-ray diffraction, UV–visible spectroscopy, Raman spectroscopy, Hall measurement, X-ray photoelectron spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy etc. Low angle X-ray diffraction analysis showed that the films are polycrystalline with hexagonal wurtzite structure and which was further confirmed by Raman spectroscopy analysis. Its preferred orientation shifts from (102) to (002) with increase in RF power. The average grain size was found in the range of 15–21 nm over the entire range of RF power studied. The FE-SEM analysis showed that grain size and surface roughness of ZnO:Al films increase in with increase in RF power. The UV–visible spectroscopy analysis revealed that all films exhibit transmittance >85 % in the visible region. The optical band gap increases from 3.37 to 3.85 eV when RF power increased from 75 to 225 W. Hall measurements showed that the minimum resistivity has been achieved for the film deposited at 200 W. The improvement in the electrical properties may attribute to increase in the carrier concentration and Hall mobility. Based on the experimental results, the RF power of 200 W appears to be an optimum sputtering power for the growth of ZnO:Al films. At this optimum sputtering power ZnO:Al films having minimum resistivity (8.61 × 10−4 Ω-cm), highly optically transparent (~87 %) were obtained at low substrate temperature (60 °C) at moderately high deposition rate (22.5 nm/min). These films can be suitable for the application in the flexible electronic devices such as TCO layer on LEDs, solar cells, TFT-LCDs and touch panels.

Influence of RF Power on Optical and Surface Properties of the ZnO Thin Films Deposited by Magnetron Sputtering

Influence of RF Power on Optical and Surface Properties of the ZnO Thin Films Deposited by Magnetron Sputtering

Magnetron sputtering process of carbon-doped α-Fe2O3 thin films for photoelectrochemical water splitting

Thin films of α-Fe2O3 doped with carbon have been fabricated on F-doped SnO2 glass substrate by magnetron sputtering process via DC power on the pure Fe target (99.99%) combined with RF power on the pure graphite target (99.99%). The influences of RF power (0, 40, 80 and 120W) on optical, structural and photoelectrochemical (PEC) characteristics have been investigated. The as-obtained samples after annealing in Ar ambient were analyzed by scanning electron microscopy, X-ray diffraction (XRD), Raman spectra, UV–visible spectra and electrochemical analysis. After annealing, all samples revealed only hematite characteristics in XRD pattern and Raman spectra. Thickness of annealed thin films was ∼350nm measured via SEM cross-section image. The optical band gap and carrier concentration of samples were in the range of 2.13–2.16eV and 6.28×1017 to 3.11×1018cm−3, respectively. Based upon our observations, the 4.56at.% carbon-doped α-Fe2O3 thin film deposited via 80W RF power has a better PEC response with photocurrent density of ∼1.18mA/cm2 at 0.6V vs. SCE. This value was about three times higher than the un-doped film (0W of RF power, reference sample). Observed higher photocurrent density was likely due to a suitable carbon-doping concentration causing a higher carrier concentration.

N-polar AlN thin layers grown on Si(111) by plasma-assisted MBE

The influence of RF power on the growth of N-polar AlN thin layers on Si(111) by plasma-assisted molecular beam epitaxy was systematically studied. The surface reconstruction of AlN was 1 × 1 for samples grown at RF power of 350–450 W, while samples grown at lower power of 150–300 W had 3 × 6 reconstruction. All samples demonstrate smooth surface with root mean square roughness less than 1 nm. The 45 nm thick AlN sample grown at RF power of 150 W has the best structural quality. The screw and edge dislocation densities estimated for this sample were 1.4 × 109 and 5.9 × 109 cm−2, respectively.