Radio Frequency Magnetron Sputtering Method Research Articles

Wettability, Surface Morphology and Structural Properties of β-FeSi₂ Films Manufactured Through Usage of Radio-Frequency Magnetron Sputtering.

In this research, β-FeSi₂ thin films were manufactured onto Si(111) wafer substrates through the usage of radio-frequency magnetron sputtering (RFMS) method at 2.66 × 10-1 Pa of sputtering pressure. The substrate temperatures were varied at 500 °C, 560 °C, and 600 °C. The Raman lines of the β-FeSi₂ fabricated at 500 °C revealed the peaks at the positions of ~174 cm-1, ~189 cm-1, ~199 cm-1, ~243 cm-1, ~278 cm-1, and ~334 cm-1. For the higher substrate temperatures of 560 °C and 600 °C, the Raman peaks of ~189 cm-1, ~243 cm-1, and ~278 cm-1 were shifted toward higher Raman positions. The surface view of the films was observed with several grains over the β-FeSi₂ film surface at all substrate temperatures. The average grain size of the films for the samples deposited at 500 °C and 560 °C was in the range of 28 to 30 nm, where the size was enlarged to 36 nm at 600 °C of substrate temperature. The root mean square roughness were 10.19 nm, 10.84 nm, and 13.67 nm for the β-FeSi₂ film surface prepared at the substrate temperatures of 500 °C, 560 °C, and 600 °C, respectively. The contact angle (CA) values were 99.25°, 99.80°, and 102.00° for the created samples at 500 °C, 560 °C, and 600 °C, respectively. As the acquired CA values, all β-FeSi₂ samples exhibited a hydrophobic property with CA in the range of 90° to 150°. Consequently, the produced β-FeSi₂ film surface employing the RFMS method indicated a potential to be employed in a hydrophobic coating application.

Effect of the Sputtering Power on the Structure, Morphology and Magnetic Properties of Fe Films

In this paper, the radio frequency (RF) magnetron sputtering (MS) method was utilized to fabricate multiple sets of the iron film samples under different sputtering powers. With the help of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and vibrating sample magnetometer (VSM), how the sputtering power affected the structure, morphology and magnetic properties of the iron film was studied. XRD results showed that all Fe films have a polycrystalline bcc structure and (110) preferred orientation. According to the Bragg equation calculation, the larger the sputtering power, the larger the average grain size, which is consistent with the results of AFM particle size analysis. The main reason is that the sputtering power affects the grain growth mode. As the sputtering power increases, it gradually changes from a small island-like growth to a thick columnar growth. However, from the surface morphology and height profile, we saw that the iron film deposited under 230 W had the most uniform grain size distribution and the grain size was relatively small. This is why thin films deposited under this condition have the best soft magnetic properties. The saturation magnetization (Ms) reaches 1566 emu/cm3, coercivity (Hc) is 112 Oe, and squareness ratio (Mr/Ms) is 0.40. Therefore, iron film prepared under 230 W has good comprehensive properties (highest Ms, lower Hc and Mr/Ms) that provide an experimental basis for further thin film research work.

Adsorption mechanism of water molecules on the surface of ZnO-SAW sensors

In the present study, the ZnO thin film was deposited on the surface acoustic wave (SAW) chip for sensitive humidity sensors by using radio frequency magnetron sputtering method. The microstructure of the ZnO thin film was characterized by using scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD). The ZnO film exhibited rough morphology with the average thickness of about 0.3 μm. The humidity-sensing properties of the sensors were examined by changing the relative humidity (RH) within the range of 20%–60% RH at ambient temperature. The resonant frequency shifts increased gradually with the rising of RH levels. It was found that the ZnO-SAW sensors showed high sensitivity, mainly owing to the formation of the liquid water layer and superposition effect of water molecules (WMs). Moreover, the density functional theory (DFT) calculation revealed that the adsorption and desorption of WMs on the ZnO film were physical processes.

The multiferroics in (111)-orientated PbTiO3:ϵ-Fe2O3 nanocomposite thin film

Multiferroic materials draw more and more attention due to their potential applications in novel multifunctional instruments and devices. In nanocomposite thin films, the ferroelectric and magnetic orders can be manipulated by orientation and strain, which will affect the multiferroics. In this letter, we reported an epitaxial PbTiO3:ϵ-Fe2O3 composite thin film with 20 nm thickness, which was fabricated on (111)-oriented Nb:SrTiO3 substrate by radio frequency magnetron sputtering method. The nanocomposite film presents both ferroelectric (Pr ≈ 19 µC cm−2) and ferromagnetic (Ms ≈ 25 emu cc−1) properties at room temperature. The combination of PbTiO3 and ϵ-Fe2O3 distinctly reduced the magnetic coercive field of the ϵ-Fe2O3. Piezoresponse force microscopy demonstrated that the composite film possessed excellent uniformity and surface quality, which is significant to the application of multifunctional precision devices.

Effect of RF sputtering power and vacuum annealing on the properties of AZO thin films prepared from ceramic target in confocal configuration

Aluminum-doped zinc oxide (AZO) thin films are deposited on glass substrate by radio frequency (RF) magnetron sputtering method in confocal configuration at room temperature (RT). Several techniques are used to investigate the effects of sputtering power, from 50 to 300 W, on structural, optical and electrical properties. It is found, from Grazing Incidence X-Ray Diffraction (GIXRD) analysis, that the sputtering power has a great influence on the crystalline quality of AZO films. A preferential orientation along the c-axis is obtained at lower sputtering power of 50 W. XPS analysis confirms the existence of only Zn and Al in the oxidized state in accordance with the XRD results. SEM and AFM observations of AZO films reveal dense and homogenous distribution of small grains on the surface. Analysis by UV–Vis–NIR spectroscopy at RT reveals that the average optical transmittance in the visible range (400–800 nm) of the AZO thin films is higher than 75%. Hall-effect measurements put into evidence that the electrical resistivity of the films increases with the increase of the sputtering power. A low resistivity of 1.65 × 10−3 Ω cm is obtained for the lowest sputtering power (50W). Moreover, AZO thin film deposited at 50 W and annealed for 1h at 400 °C under vacuum shows a lower resistivity of 5.75 × 10−4 Ω cm, an average optical transmission above 86% and a high figure of merit (ФTC) value of 3.4 × 10−3 Ω−1sq which suggests that the fabricated AZO thin films are promising for optoelectronic devices in the UV region.

Annealing temperature induced improved crystallinity of YSZ thin film

Six YSZ thin films (YSZTFs) were prepared at varied annealing temperature (380 °C to 600 °C) by radio frequency magnetron sputtering method. Glancing angle x-ray diffraction (GAXRD) pattern revealed the polycrystalline nature of all films with crystallite size in the range of 9 to 15 nm. Sample annealed at 400 °C displayed the lowest microstrain (0.262) and crystallinity (60%). FESEM images disclosed dense, homogeneous and crack free growth of annealed samples compared to as-deposited one. EDX spectra detected the right elemental compositions of films. AFM images showed growth evolution of YSZ grains with size range between 0.2 to 5 nm and improved films’ surface roughness. HRTEM measurement of the studied YSZTFs exhibited lattice orientation and atomic structure of nucleated YSZ nanocrystallites. Furthermore, film annealed at 500 °C divulged less oriented structure because of dislocation.

Fabrication and characterization of Mg-doped ε-Ga2O3 solar-blind photodetector

In this work, Mg-doped ε-Ga2O3 (3.38 cation % of Mg) solar-blind photodetector is fabricated by using radio-frequency magnetron sputtering and metal-organic chemical vapor deposition methods on sapphire substrate. The results show that the Mg-doped ε-Ga2O3 thin film solar-blind photodetector exhibit a photo-to-dark current ratio of 1.68×102, responsivity of 77.2 mA/W, specific detectivity of 2.85×1012 Jones, and external quantum efficiency of 37.8% at 5 V under 40 μW/cm2 254 nm ultraviolet light illumination, as well as the stable light switching property driven by different applied voltages and light intensities. The achieved Mg-doped ε-Ga2O3 solar-blind photodetector is promised to advance relevant developments of the metastable Ga2O3 optoelectronic devices.

Negative capacitance phenomena in Au/SrTiO3/p-Si heterojunction structure

In this study, temperature- and frequency-dependent capacitance and conductance measurements of the Au/SrTiO3/p-Si heterojunction structure were examined. Strontium titanate (SrTiO3) thin films were deposited on cleaned p-type (100)-oriented silicon substrates using radio frequency (RF) magnetron sputtering method at a substrate temperature of 500 °C. The temperature-dependent reverse and forward bias C–V and G/ω$$-V$$ characteristics of the Au/SrTiO3/p-Si heterojunction structure was realized in the temperature range of 110–350 K (by step 30 K) at 1 MHz. The frequency-dependent reverse and forward bias C–V and G/ω$$-V$$ characteristics of the Au/SrTiO3/p-Si heterojunction structure was realized in the frequency range of 100–900 kHz (by step 100 kHz) at room temperature. It has been demonstrated that Au/SrTiO3/p-Si heterojunction structure exhibits negative capacitance (NC) behavior as a result of both temperature- and frequency-dependent capacitance measurements due to the reduction of interface charges, ionization states and series resistance in the forward bias voltage. In addition, it was shown that it exhibits an intersection point in the forward bias voltage of both temperature and frequency-dependent capacitance measurements. In temperature and frequency-dependent admittance spectroscopy measurements of Au/SrTiO3/p-Si heterojunction structure was observed NC phenomenon.

Capacitance Properties in Ba0.3Sr0.7Zr0.18Ti0.82O3 Thin Films on Silicon Substrate for Thin Film Capacitor Applications

Crystalline Ba0.3Sr0.7Zr0.18Ti0.82O3 (BSZT) thin film was grown on Pt(111)/Ti/SiO2/Si substrate using radio frequency (RF) magnetron sputtering. Based on our best knowledge, there are few reports in the literature to prepare the perovskite BSZT thin films, especially using the RF magnetron sputtering method. The microstructure of the thin films was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and capacitance properties, such as capacitance density, leakage behavior, and the temperature dependence of capacitance were investigated experimentally. The prepared perovskite BSZT film showed a low leakage current density of 7.65 × 10−7 A/cm2 at 60 V, and large breakdown strength of 4 MV/cm. In addition, the prepared BSZT thin film capacitor not only exhibits an almost linear and acceptable change (ΔC/C ~13.6%) of capacitance from room temperature to 180 °C but also a large capacitance density of 1.7 nF/mm2 at 100 kHz, which show great potential for coupling and decoupling applications.

Effects of different annealing temperatures on the physical, optical, and electrical characteristics and chemical bonds of Ga and F Co-doped ZnO films

In this study, we would investigate the effect of annealing temperature on the physical, optical, and electrical characteristics and chemical bonds of F- and Ga-co-doped ZnO (FGZO) Films. At first, 3 wt% Ga2O3 was mixed with 97 wt% ZnO to form the Ga-doped ZnO ceramic target, and the radio frequency (RF) magnetron sputtering method was used to deposit FGZO films. 0.2% CF4 flow rate (CF4/Ar) was controlled using the mixing gas of CF4 and pure Ar, and the mixing gas was introduced during the deposition process, which acted as the source of F− ions. FGZO films were deposited on the EagleXG glass and the films’ thickness was about 300 nm by controlling the deposition time. After FGZO films were deposited, they were annealed at 200, 300, and 400 °C. A comparative study of composition of FGZO films was investigated using secondary-ion mass spectrometry (SIMS) to analyze the distributions of F, Zn, Ga, and C elements, respectively, as the annealing temperature was changed. Another comparative study of FGZO films was that we proposed a modified Burstein-Moss (BM) equation to investigate the relationship between the carrier concentration and the shift of optical energy bandgap. Third comparative study of surfaces of FGZO films were investigated using X-ray photoelectron spectroscopy (XPS) to find the variations of the chemical bonds.

Structural, optical and sensing properties of ZnS thick films deposited by RF magnetron sputtering technique at different powers

PurposeThis study aims to carry out the deposition of zinc sulfide (ZnS) thick films on glass and silicon (100) substrates using radio frequency (RF) magnetron sputtering method at different powers. Film structure has been analyzed by X-ray diffraction (XRD); the patterns showed that the films possesses a cubic structure with (111) preferred orientation. Photoluminance (PL) intensity of the films has been related to the crystallinity, which is varied with the power.Design/methodology/approachScanning electron microscope (SEM) images have been used to discover the films’ morphology. The stoichiometry has been confirmed by energy dispersive X-ray spectroscopy (EDX) analysis. MicroRaman spectroscopy has been used to validate the film structure. Gas-sensing studies were carried out by means of a static gas chamber to sense acetone, ethanol, methanol, H2O and NH3 vapor in air ambient.FindingsZnS has a stoichiometric and cubic structure. The band gaps and photoluminance intensity of the films are correlated with the crystallinity, which is varied with the power. The EDX analysis approved the stoichiometry of the prepared films. Acetone, ethanol, humidity (H2O), methanol and NH3 vapor gases were used to justify the sensing properties at 25°C of the thickest ZnS film.Originality/valueHigh-quality ZnS films have been obtained at different powers without annealing. Gases sensing properties at 25°C are justified for deposited ZnS films using acetone, ethanol, humidity (H2O), methanol and NH3 vapor gases. It reveals good response for NH3 and humidity vapors at room temperature; the sensing functioning at this temperature was attractive in recent research.

Low frequency noise characteristics of resistor- and Si MOSFET-type gas sensors fabricated on the same Si wafer with In2O3 sensing layer

By analyzing the Low Frequency Noise (LFN) characteristics of the resistor-type and the Si metal oxide semiconductor Field Effect Transistor (FET)-type gas sensors fabricated on the same wafer, the intrinsic device noise and the additional noise generated from the gas reaction are systemically examined. Sensing material, n-type Indium-Oxide (In2O3) film, is deposited using the radio frequency magnetron sputtering method. Unlike the FET-type gas sensor, the LFN characteristics of the resistor-type gas sensor are affected by the deposition condition of the sensing material. It is shown that the FET-type sensor has at least 10 times less LFN power than the resistor-type gas sensor despite its smaller size. Gas to Air Noise Ratio (GANR) is introduced as a new figure of merit to evaluate and compare the LFN characteristics during the gas reaction in both resistor- and FET-type gas sensors with the sensing layer prepared by different process conditions. The GANRs of the resistor-type sensors range from ∼2 to 4, which demonstrates that the reaction between the gas molecules and the sensing material generates a fluctuation that exceeds the intrinsic noise of devices. However, the FET-type gas sensors have a constant value of GANR (∼1) regardless of the operation region, showing that the FET-type gas sensors have better performance in terms of noise.

Growth Control of WS2: From 2D Layer by Layer to 3D Vertical Standing Nanowalls.

Large area 2D WS2 has been grown successfully by radio frequency magnetron sputtering (RFMS) method. First, in order to investigate the pressure dependence on the grown WS2 samples, WS2 were grown at 5 different growth pressures, 5, 10, 15, 20, and 25 mTorr. It has been observed that the surface morphology changes for the samples grown at higher growth pressures, 15, 20, and 25 mTorr. Vertically standing nanowall (NW)-like structures have been formed at these relatively high growth pressures. It has also been observed that the (002) plane is highly dominant, which means layer by layer growth parallel to the substrate, for the sample grown at 20 mTorr. X-ray photoelectron spectroscopy (XPS) measurements revealed an increasing atomic percentage of the S element to W element, S/W, ratio in thin films, as the growth pressure increases. Growth dynamics of WS2 has been investigated by time-dependent-growth WS2 samples, 5, 10, 20, 40, and 80 s under 20 mTorr pressure. It has been shown by atomic force microscopy, scanning electron microscopy, and transmission electron microscopy that a highly smooth surface has been achieved in the samples grown for the duration of 5 and 10 s. Raman mapping measurements on the sample grown at 5 s have revealed large area homogeneous growth. As the growth time gets longer, the NWs emerge on the surface at some nucleation points. Only the peak that belongs to the (002) plane has been observed for samples grown at 5 and 10 s by the X-ray diffraction (XRD) measurements. XRD measurements have revealed the appearance of turbostratic peaks of (11l) and (10l) as the thickness increases. Photoluminescence measurements have indicated near-band-edge emission centered at 630 nm for only 5 and 10 s samples.

Platinum nanoparticles on HOPG surface modified by 380 keV Ar+ irradiation: TEM and Raman studies

ABSTRACTThe ion beam-induced defects in carbon supports for platinum (Pt) nanoparticles have been found to enhance the catalytic activity. Highly oriented pyrolytic graphite (HOPG) was irradiated with 380 keV argon ions (Ar), and Pt nanoparticles were then deposited on it by a radio frequency (rf) magnetron sputtering method. The Pt nanoparticle size on Ar-irradiated HOPG and the carbon structure at the interface were investigated by transmission electron microscope (TEM) and Raman spectroscopy, respectively. The observed size of Pt nanoparticles on the irradiated HOPG was larger than that on the non-irradiated HOPG. Raman spectra indicated that vacancy-like defects were formed on the HOPG surface by Ar-irradiation at the fluences between and ions/cm, and sp defects were induced by irradiation more than ions/cm. These defective structures on the HOPG would promote the Pt particle growth.

Oxide charge evolution under crystallization of amorphous Li–Nb–O films

Li–Nb–O amorphous films were deposited onto Si substrates by the radio-frequency magnetron sputtering method in an Ar environment and an Ar(60%)+O 2 (40%) gas mixture. A positive effective fixed oxide charge Q eff having negative, -Q eff , and positive, +Q eff , components, exists in the as-grown heterostructures. -Q eff is located near the substrate/film interface, whereas + Q eff is determined by a deficit of Li and O (vacancies) in the bulk of Li–Nb–O films. As-grown films crystallized under thermal annealing (TA) at temperatures up to 600 °C and revealed the formation of polycrystalline LiNbO 3 . TA at about 520 °C resulted in the formation of the second phase LiNb 3 O 8 , increasing + Q eff , and compensating -Q eff entirely. The dielectric constants of the as-grown films exhibit two peaks at the annealing temperatures of 450 °C and 550 °C, which are attributed to the total crystallization and recrystallization of the LN films under TA, respectively.

Effect of Zr Target Current on the Mechanical and Tribological Performance of MoS2–Zr Composite Lubricating Coatings

To improve the tribological properties of pure MoS2 coating, the MoS2–Zr composite lubricating coatings were prepared on the WC/TiC/Co carbide surface utilizing radio frequency magnetron sputtering method combining with multiple arc ion plating technology. The effects of different Zr target currents on the surface morphologies, roughness, Zr content, adhesive force, thickness, microhardness and tribological behaviors of the composite coatings were systematically investigated. Results showed that the properties of MoS2 coating can be remarkably enhanced through co-deposition of a certain amount of Zr. As the Zr target current increased, the Zr content, surface roughness, thickness, and micro-hardness gradually increased, while the adhesive force of coatings increased first and then decreased. The friction behaviors and wear modes of the composite coatings both varied obviously with the increase of Zr current. The mechanism was mainly attributed to the different components and mechanical properties of the coatings caused by various Zr current.

Surface acoustic wave humidity sensor based on three-dimensional architecture graphene/PVA/SiO2 and its application for respiration monitoring

A quartz surface acoustic wave (SAW) delay line humidity sensor based on three-dimensional architecture graphene (3DAG)/polyvinyl alcohol (PVA)/SiO2 layered sensing film have been proposed and applied in respiration monitoring. An amorphous SiO2 nanolayer was deposited on the total surface of the SAW delay line by radio frequency magnetron sputtering method as a protect coating and sensing film. Then, 3DAG grown on Ta substrate using CVD method was in-situ transformed to the delay area of the SAW device using PVA film to construct a humidity sensor. The prepared humidity sensor exhibits high sensitivity especially under high relative humidity range of 55 %–90 % due to the synergetic effects of the viscoelastic effect of the PVA film, the large absorption and transportation effect of 3DAG, and the mass loading effect of the SiO2. The humidity sensor also has short response and recovery times, good stability, repeatability, and selectivity. Furthermore, the developed humidity sensor was used for respiration monitoring and exhibit excellent capability of monitoring different respiration rates and depths. The respiration variations before and after water drinking can also be recognized by the sensor.

Aluminum doped zinc oxide (AZO)-based pressure sensor

The feasibility of using aluminum-doped zinc oxide (AZO) as a piezoresistive pressure sensor material is reported. AZO has attracted a great deal of attention in many applications because of its nontoxicity, abundancy and lower cost than other materials such as indium tin oxide (ITO). The AZO films were deposited on polyethylene (PE) substrates by a radio-frequency (rf) magnetron sputtering method and they were used as the diaphragms of the pressure sensors. The piezoresistive sensor was tested for different pressures in vacuum and gage pressure conditions. The response characteristics indicated that resistance increased with the bending of the AZO layer in both compressive and tensile operation modes. The sensor characteristics exhibited that the AZO piezoresistive sensor can be used to measure ambient pressure quantitatively. This investigation indicated that AZO can be used as an alternative material for the fabrication of pressure sensors.

Microstructural characterization of BN thin films using RF magnetron sputtering method

Boron nitride films were prepared via radio frequency (RF) magnetron sputtering from a hexagonal boron nitride (h-BN) target on 316L stainless steel substrates. Deposition process was carried out in a three different Ar and N2 mixture environment regimes. The composition and microstructure morphology of the BN films at varied mixing ratio of Ar and N2 plasma were investigated by XRD (X-Ray Diffraction) and Scanning Electron Microscopy (SEM) techniques respectively. Phase identification of c-BN was done with Fourier transform infrared spectroscopy (FTIR). The objective of the study was to investigate the effects of varying the ratio of N2 gas on the structural morphology and the formation of c-BN phase was studied. Using QAr/QN2 –5/1 ratio an improved microstructure quality and more c-BN phase formation suggesting a fundamental strategy for achieving high-quality c-BN films. The thickness of the coating was measured by calottes.

Preparation of TAT tri-layer insulating film on automotive glass using magnetron sputtering method

In this paper, tri-layer structured films of titanium dioxide, silver and titanium dioxide were deposited on ordinary glass using radio frequency magnetron sputtering method to serve as thermal insulation films on automotive glass. The transmittance and thermal insulation of the prepared insulating films were changed by altering the deposition time of silver and titanium dioxide. The transmittance, absorbance and thermal insulation of the insulating films to visible light and infrared light were measured by ultraviolet-visible spectrophotometer and infrared spectrometer. The thermal conductivity of the films with different transmittances was tested by the thermal conductivity tester. The insulating films with lower thermal conductivity were screened out for analysis, and on this basis, the experiment was improved continuously. The total solar energy rejection rate was calculated subsequently. After summarizing the whole experiment process, the improvement measures were put forward to optimize the production of insulation films on automotive glass. The results show that the transmittance of TiO2-Ag-TiO2 tri-layer insulation film is 70.19%, and the solar energy rejection rate is 67.80%. The transmittance meets the national standard and the total rejection rate is also higher than many of the insulation films on the market.