Influence Of Radio Frequency Power Research Articles

Influence of RF power in the sputter deposition of amorphous InGaZnO film on the transient drain current of amorphous InGaZnO thin-film transistors

The device electrical and transient current characteristics of the amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) are comprehensively investigated according to the radio-frequency (RF) power during the sputter-deposition of IGZO active film. The RF power dependencies of the oxygen vacancy (VO) concentration in IGZO and the surface morphology of IGZO film are analyzed through X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). According to the RF power change in the range of 100 ∼ 250 W, the optimal point in terms of threshold voltage (VT), ON current (Ion), field-effect mobility in the linear region (μFE_lin), hysteresis voltage (VHys), and the VT shift under current stress (ΔVT) is found to be 200 W. The existence of the optimal power condition originates from the RF-power dependencies of the electron carrier concentration, the density of electron traps in gate insulator (GI), and the interface trap density related to surface roughness.Furthermore, compared to the direct current (DC) current stress (CS) condition, it is found that when VGS rises rapidly, a total transient current ΔID can be decomposed into three components, i.e., ΔIOS, ΔIBOOST, ΔIDEG. While ΔIOS is attributed to the non-quasi static Fermi-level rising, ΔIBOOST and ΔIDEG result from the donor creation in IGZO and the electron trapping into GI and interface. Noticeably, the occurrence level of each component changes sensitively according to RF power.Our result suggests that the 200 W device has the least overshoot of transient current and shows the best reliability in terms of deterioration due to transient current characteristics.

Improving Mechanical and Tribological Behaviors of GLC Films on NBR under Water Lubrication by Doping Ti and N

Water lubrication has been widely used in marine equipment, where rubber bearings and seals suffer intense friction and severe wear under mixed and boundary conditions. It has good research prospects and practical value to study the composite of amorphous carbon on water lubrication rubber to improve lubrication and reduce wear. In this work, modified graphite-like carbon films incorporated with titanium and nitrogen ((Ti:N)-GLC) were integrated on nitrile butadiene rubber (NBR) with multi-target magnetron sputtering. Direct current (DC) sputtering of graphite target was used as the carbon source. The incorporation of Ti and N elements was accomplished by using radio frequency (RF) magnetron sputtering of three different targets: Ti, TiC and TiN, to optimize the mechanical and tribological performance. This work is aimed to clarify the modification mechanism of Ti and N incorporation and obtain the optimum scheme. The influence of RF power on surface topography, chemical composition, mechanical properties and tribological properties was investigated by SEM, XPS, Raman spectra, nanoindentor and tribometer. The consequences revealed that the characteristics of films depend on RF target types and power. For the Ti-C and TiC-C series, when RF power is 100 W and below, with low content of Ti (6 at.%~13 at.%) and N (around 10 at.%), the incorporation of Ti and N optimizes the surface topology, improves the mechanical properties and maintains excellent adhesion to NBR substrate. The tribological and wear behaviors of (Ti:N)-GLC films are better than GLC films under mixed and boundary lubrication. When RF power grows to 200 W, the dopants result in the deterioration of surface and mechanical properties, followed by worse lubrication and wear behaviors. For TiN-C series, the incorporation of TiN takes no advantage over GLC films, even worse in the case of high RF power. Overall, the incorporation of Ti or TiC by magnetron sputtering in Ar/N2 atmosphere is an effective modification method for GLC films on NBR to improve mechanical and tribological behaviors.

The Influence of RF power, pressure and substrate temperature on the energy gap to vanadium oxide at tallness wave stir 290 nm of RF sputtered

In this work, the (V2O5) films were deposited on glass substrates which produce by using "radio frequency (RF)"power supply and Argon gas technique and the nano-thin film deposition is obtained from a V2O5 target (5 mm in diameter and 5mm thickness) by the gradual variation of sputtering power 150 Watt and variation pressure (0.03, 0.05 and 0.007) Torr. The Energy Gap were investigated by, UV spectroscopy at "radio frequency" (RF) power ranging from 150 Watt and and substrate temperature (359, 373,473 and 573 K) and gas pressure (0.03, 0.05 and 0.007 Torr). The Energy Gap of the Vanadium Oxide thin film deposited by RF magnetron sputtering were analysis by UV-Visible spectroscopy shows that the average transmittance of all films in the range 40-65 %. When the thickness has been increased the transhumance was decreased from 65-40%. The values of energy gap were decreased from (3.02-2.7 eV) with the increase of thickness the films in relation to an increase in power. The energy gap decreased (2.8 - 2.7) eV with an increase in the substrate temperature respectively and the pressure.

The Influence of RF power, pressure and substrate temperature on optical properties of RF Sputtered vanadium pentoxide thin films

The V2O5 films were deposited on glass substrates which produce using "radio frequency (RF)"power supply and Argon gas technique. The optical properties were investigated by, UV spectroscopy at "radio frequency" (RF) power ranging from 75 - 150 Watt and gas pressure, (0.03, 0.05 and 0.007 Torr), and substrate temperature (359, 373,473 and 573) K. The UV-Visible analysis shows that the average transmittance of all films in the range 40-65 %. When the thickness has been increased the transhumance was decreased from (65-40) %. The values of energy band gap were lowered from (3.02-2.9 eV) with the increase of thickness the films in relation to an increase in power, The energy gap decreased (2.8 - 2.7) eV with an increase in the pressure and substrate temperature respectively.

Exploring the photo paper as flexible substrate for fabrication of a-Si:H based thin film solar cells at low temperature (110 °C): Influence of radio frequency power on opto-electronic properties

The effect of variation of radio frequency (rf) power on the structural, optical and electronic properties of intrinsic hydrogenated amorphous silicon (a-Si:H) films deposited at very low substrate temperature (Ts) 110 °C were studied. These films were prepared varying rf power (40-70 W) on borosilicate glass, photo paper and c-Si substrates using rf-plasma enhanced chemical vapour deposition (13.56 MHz) technique. All films show amorphous structure confirmed by Raman measurement and also supported by spectroscopic ellipsometry (SE) measurements. SE results show that at higher rf power, amplitude of peak decreases and broadening increases due to increase in void density. Intrinsic layer with optimized rf power was used for fabricating n-i-p solar cell on flexible polyethylene terephthalate (PET), polyimide (PI), photo paper and rigid glass. The efficiency of solar cells fabricated on flexible PET and PI is 3.30% and 3.36%, which is close to 3.82% on rigid glass. In case of solar cells on photo paper, an efficiency of ~ 1.08% was obtained. The studies show that it is possible to fabricate a-Si:H based solar cells on photo paper and other substrates at very low Ts.

Influence of radiofrequency power on structural, morphological, optical and electrical properties of magnetron sputtered CdO: Sm thin films as alternative TCO for optoelectronic applications

Highly transparent and conducting samarium doped cadmium oxide (CdO: Sm) thin films were deposited on glass substrates at room temperature by radio frequency (RF) magnetron sputtering technique using CdO(90 wt%): Sm2O3(10 wt%) mixed alloy target in pure argon atmosphere. The influences of RF power and Sm incorporation on structural, morphological, optical and electrical properties of the films were investigated. X-ray diffraction analysis revealed that the deposited films are polycrystalline nature and RF power has a large impact on the preferred orientation of the films. The X-ray photoelectron spectroscopy studies confirmed the presence of divalent cadmium (Cd2+) and trivalent samarium (Sm3+) in the deposited film. It is found from the atomic force microscopic analysis that the films were highly smooth with low roughness value of about1.3 nm. High transmittance value greater than 80% was retained by the films in visible and near infrared regions and the band gap value decreased with the increase of RF power by quantum confinement. At the moderate RF power of 200 W, the film has low resistivity of the order of 1.283 × 10−4 Ω cm, high mobility 157.8 cm2/V and a high figure of merit 769.04 (Ω cm2)−1 which could be used as an alternative TCO layer for future optoelectronic devices.

A study on structural formation and optical properties of Zn1-xCdxO thin films synthesized by the DC and RF reactive magnetron co-sputtering

The Zn1-xCdxO thin films were prepared on quartz by the direct current (DC) and radio frequency (RF) reactive magnetron co-sputtering technique with Zn and Cd metal targets. The influence of RF power on Cd target (PCd) on the structure and optical properties of Zn1-xCdxO films was investigated by using X-ray diffraction (XRD), transmission electron microscope (TEM), optical absorbance and photoluminescence (PL) measurements. The concentration and chemical states of Cd in films have been confirmed by energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) analysis. The results indicated that as the PCd varied from 0 to 120 W, all the Zn1-xCdxO thin films had a hexagonal wurtzite structure of pure ZnO and highly (002) preferred orientation, the Cd relative content in film is increased and the Zn relative content is decreased. Correspondingly, the optical band-gap of Zn1-xCdxO thin films with hexagonal wurtzite structure are tuned from 3.24 (PCd = 0) to 2.82 eV (PCd = 120 W). The location of the near-band-edge (NBE) emission peaks shift toward lower energy side from 388 to 440 nm, which is attributed to the decrease of band gap caused by Cd substitution.

Influence of RF power on performance of sputtered a-IGZO based liquid crystal cells

The influence of radio-frequency (RF) power on sputter-deposited amorphous indium gallium zinc oxide (a-IGZO) films and the corresponding liquid crystal cell performances have been investigated. The inorganic films were used as alternative alignment layers for liquid crystal display cells. The columnar growth of film was achieved by non-contact, fixed oblique deposition using RF sputtering at the power of 50W, 60W and 70W. The experiments have been carried out to compare the physical characteristics with those of the traditional polyimide (PI) alignment layers used for liquid crystal cells. The cell performances in voltage-transmittance, contrast ratio, and response time were all evaluated. The liquid crystal pretilt angle has been determined to be about 13° using 70W power deposited a-IGZO film. It was 6° for the 60W deposited film and only 1.5° for the PI alignment film. The experimental cell rise time and fall time was 1.25ms and 2.96ms, respectively. Thus, a very quick response time of 4.21ms has been achieved. It was about 6.62ms for the PI alignment control cell.

Characteristics of ultra low-k nanoporous and fluorinated silica based films prepared by plasma enhanced chemical vapor deposition

Low dielectric constant (low-k) silica based films were deposited on p-type silicon and polycarbonate substrates by radio frequency (RF) plasma enhanced chemical vapor deposition method at low temperature. A mixture of tetraethoxysilane vapor, oxygen, and tetrafluoromethane (CF4) was used for the deposition of the films in forms of two structures called as SiOxCy and SiOxCyFz. Properties of the films were controlled by amount of porosity and fluorine content in the film matrix. The influence of RF power and CF4 flow on the elemental composition, deposition rate, surface roughness, leakage current, refractive index, and dielectric constant of the films were characterized. Moreover, optical emission spectroscopy was applied to monitor the plasma process at the different parameters. Electrical characteristics of SiOxCy and SiOxCyFz films with metal-oxide-semiconductor structure were investigated using current-voltage analysis to measure the leakage current and breakdown field, as well as capacitance-voltage analysis to obtain the film's dielectric constant. The results revealed that SiOxCy films, which are deposited at lower RF power produce more leakage current, meanwhile the dielectric constant and refractive index of these films decreased mainly due to the more porosity in the film structure. By adding CF4 in the deposition process, fluorine, the most electronegative and the least polarized atom, doped into the silica film and led to decrease in the refractive index and the dielectric constant. In addition, no breakdown field was observed in the electrical characteristics of SiOxCyFz films and the leakage current of these films reduced by increment of the CF4 flow.

The influence of RF power on the electrical properties of sputtered amorphous In—Ga—Zn—O thin films and devices

The influence of radio frequency (RF) power on the properties of magnetron sputtered amorphous indium gallium zinc oxide (a-IGZO) thin films and the related thin-film transistor (TFT) devices is investigated comprehensively. A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined. The results prove that the deposition rate sensitively depends on RF power. In addition, the carrier concentration increases from 0.91 × 1019 to 2.15 × 1019 cm−3 with the RF power rising from 40 to 80 W, which may account for the corresponding decrease in the resistivity of the a-IGZO thin films. No evident impacts of RF power are observed on the surface roughness, crystalline nature and stoichiometry of the a-IGZO samples. On the other hand, optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W, as is supposed to result from the carrier-induced band-filling effect. The rise in RF power can also affect the performance of a-IGZO TFTs, in particular by increasing the field-effect mobility clearly, which is assumed to be due to the alteration of the extended states in a-IGZO thin films.

Influence of Radio Frequency Power on the Structural Properties of nc-Si Films Fabricated by VHF-PECVD

In recent years, hydrogenated nanocrystalline silicon (nc-Si:H) film has received much attention due to its potential application in various optoelectronic devices. In the present work, nanocrystalline silicon (nc-Si) films were fabricated from SiH4 diluted with H2 in very high frequency (40.68 MHz) plasma enhanced chemical vapor deposition system. The influence of radio frequency (rf) power on the structural properties of nanocrystalline silicon films has been studied. Raman spectra show that the crystallinity of the nc-Si films can be increased by promoting the rf power. But over high rf power leads to the structural deterioration of nc-Si:H film. AFM images manifest that, with the increase of deposition time, the grain size becomes larger accompanied by the decrease of the number density.

Influence of RF power on structure and electrical properties of sputtered SrHfON thin films

SrHfON thin films were prepared by radio frequency (RF) magnetron reactive sputtering under various RF power in the range of 60–150W. Effects of the RF power on structure and electrical properties of the films were investigated. Results show that the structure and electrical properties of the films are strongly affected by the RF power. The film deposited at RF power=60W is amorphous, while those deposited at RF power≥90W exhibit local crystallization. With the increasing RF power, the leakage current density increases, the dielectric constant increases initially and then decreases, whereas the flat-band voltage shift decreases initially and then increases.

Tribological properties of a-C:W film deposited by radio frequency magnetron Co-sputtering method

We deposited the tungsten doped amorphous carbon (a-C :W) film on silicon (Si) substrate by radio frequency (RF) magnetron co-sputtering method. Tungsten (W) was used as the doping metal of a-C film. Carbon and metal components were deposited simultaneously on the Si substrate by co-sputtering method, and the applied RF power on the graphite (C) was 150W and it on tungsten (W) metal target was from 20W to 50W, respectively. In this work, the influence of RF power in W target on the structural, physical, and tribologcal properties of the a-C:W films was experimentally investigated. The hardness increased with increasing RF power in W target and exhibited the maximum hardness value about 18.5GPa at the condition of RF power in W target, and the adhesion and surface roughness properties improved with increasing RF power in W target. However the friction property is declined with increasing RF power. Consequently, the improvement of physical properties in a-C:W films is associated with the enhancement of energetic ions bombardment and the increase of W contents in amorphous matrix by increasing RF power in W target.

Influence of radio frequency power on the structure and optical properties of glow discharge polymer films

Taking advantage of triple radio frequency, hydrocarbon polymer films are fabricated at different powers by the glow discharge polymerization technology. The deposition rates, the chemical structures, the atomic ratios and the optical properties are studied. The thicknesses of glow discharge polymer (GDP) films are measured by the surface profiler technology. The chemical compositions of GDP films are characterized by FT-IR spectra and element analysis. The optical properties of GDP films are investigated by UV-VIS spectra. With RF power increasing from 20 W to 60 W, the deposition rate of GDP films first increases 0.34 μ m/h, then decreases after the RF power reaches 40 W. In visible light area more than 500 nm, the optical transmittances of all GDP films are more than 90%.The optical band gaps of GDP films first decrease, then reaches the minimum at the RF power of 50 W, then increases when the RF power increases from 20 W to 60 W.

Influence of radio-frequency power on the state of H2/C4H8 glowing discharge plasma

Taking advantage of the glowing discharge technology and plasma mass spectrometry diagnosis technology, the variation rules of positive ion species and energy with power in H2/C4H8 mixture gas are investigated. The characteristic ions are measured and their forming process is discussed. The results show that the intensity of the C-H segment ions in the H2/C4H8 plasma increases with radio-frequency (RF) power increasing, the intensity reaches a maximum at an RF power of 20 W, and then reduces after the RF power has reached 25 W. The relative concentration of m/e 57 (C4H9+) is highest when the power is less than 10 W, and when the power is more than 10 W, the relative concentration of m/e 39 (C3H3+) reaches a maximum. The energy of the C-H segment ions increases gradually with the increase of RF power. The qualitative analyses of H2/C4H8 plasma composition and energy will be beneficial to improving the fabrication technology of glowing discharge polymer coating.

Spectroscopic Ellipsometry Study on HfO<sub>2</sub> Thin Films Deposited at Different RF Powers

HfO2 thin films were prepared by radio frequency (RF) magnetron sputtering at different RF powers. The influence of RF power on optical properties of HfO2 thin films were investigated by spectroscopic ellipsometry (SE) toghther with high-resolution transmission electron microscopy (HR-TEM) and Fourier transform infrared spectroscopy (FTIR). The results show that there is a SiO2 interface layer between HfO2 thin film and Si substrate. A four layer structured model consisting of SiO2 interfacial layer was used to fit the SE data. With the increasing RF power, the refractive index of the HfO2 thin films increases firstly and then decreases and, the extinction coefficient of the HfO2 thin films increases little.

Influence of radio frequency power on thermal diffusivity of plasma enhanced chemical vapor deposition-grown hydrogenated amorphous carbon thin-films

Thermal diffusivity (α) of hydrogenated amorphous carbon (a-C:H) thin-films was characterized using the picosecond thermoreflectance measurement technique in the present study. The samples were fabricated in a plasma enhanced chemical vapor deposition system with varying radio frequency (RF) discharge powers from 15 to 70 W. Chemical bonding properties of the a-C:H films were determined from the Fourier transform infrared spectra and Raman spectroscopy. Results show that α is enhanced from 0.07 to 0.20 mm2 s−1 as the RF power increases. It attributes to the dehydrogenation of film resulting from the bombardment of high-energy ion species that breaks C–H bonds at the lower power regime. Particularly at the highest RF power, however, the increase of α is more influenced by the restructuring of bonding configuration associated with the breaking up of sp2 clusters into smaller ones.

The influence of radio frequency power on the characteristics of carbon-rich hydrogenated amorphous silicon carbide films

A series of carbon-rich hydrogenated amorphous silicon carbide (a-Si1–xCx:H) films were prepared at different radio frequency (RF) powers from silane-ethylene-hydrogen plasma. The effect of the RF power on the bonding configurations and microstructures has been investigated. The grown films were characterized by a collection of techniques including Scanning Electron Microscope, Fourier transform infrared(FTIR) spectroscopy, Raman scattering and photoluminescence spectroscopy. The deposition rate increases upon RF power due to the enhancement of chemical reactivity of plasma. The carbon to silicon ratio increases, for more C2H4 molecules decompose with the enhancement of RF power and more carbon atoms are bonded into the films. Raman G peak position shifts to a higher wavenumber, which indicates that the size and concentration of sp2 carbon clusters increase as the RF power becomes stronger. Blue-green photoluminescence is detected at room temperature. The PL band can be attributed to the existence of the amorphous carbon clusters in films with high carbon concentrations.

Influence of RF power on the properties of sputtered ZnO:Al thin films

AbstractTransparent conducting, aluminium doped zinc oxide thin films (ZnO:Al) were deposited by radio frequency (RF) magnetron sputtering. The RF power was varied from 60 to 350 W whereas the substrate temperature was kept at 160 °C. The structural, electrical and optical properties of the as‐deposited films were found to be influenced by the deposition power. The X‐ray diffraction analysis showed that all the films have a strong preferred orientation along the [001] direction. The crystallite size was varied from 14 to 36 nm, however no significant change was observed in the case of lattice constant. The optical band gap varied in the range 3.44–3.58 eV. The lowest resistivity of 1.2 × 10−3 Ω cm was shown by the films deposited at 250 W. The mobility of the films was found to increase with the deposition power.

Influence of RF power on the structure and optical properties of sputtered hafnium dioxide thin films

Hafnium dioxide (HfO 2) thin films were prepared by radio frequency (RF) magnetron sputtering at various RF powers. The influence of RF power on the structure and optical properties of the HfO 2 thin films were studied systematically by X-ray diffraction (XRD), ultraviolet-visible transmission spectrum and Fourier transform infrared (FTIR) spectrum. The results show that the thin films are polycrystalline, the crystallization is improved and the crystallite size has its minimum value for the thin film deposited at the RF power of 110 W. The refractive index and band gap energy of the thin films both increase firstly and then decrease with the increased RF power. The further study reveals that the antireflective effect in certain infrared waveband, such as 3–5 μm and 8–12 μm, can be achieved in the HfO 2/Si/HfO 2 system, indicating an excellent infrared antireflective coating of HfO 2 thin film.