RF Magnetron Sputtering Method Research Articles

Improved Transparent Gas Sensor Properties of Cu-Doped SnO2 Films using O2 Plasma Treatment

Cu-doped SnO2 films were deposited on glass slide substrate using an RF magnetron sputtering method. The effects of O2 partial pressures in the deposition process and post O2 plasma treatment were assessed for optical and sensing properties. O2 partial pressures from 2% to 10% were assessed. Post-plasma treatment used a 15 mL/min O2 flow, 450 °C annealing temperature and 30 min treatment time. Optical transmission spectra showed that the films deposited at higher O2 partial pressures had higher transparency and increased band gaps from 3.08 to 3.78 eV. After O2 plasma treatment, the films showed better than optical transmission. However, when the O2 partial pressure increased to 10%, the optical transmission declined slightly because the film had higher surface roughness, smaller crystals and fewer oxygens in the parent rutile tetragonal cells, enhanced the sensor response at room temperature.

Growth of (110)-one-axis-oriented perovskite-type oxide thin films with local epitaxy on (111)SrTiO3 single crystal substrates

Thin films of BaCe0.8Y0.2O3−δ (BCYO) and SrZr0.8Y0.2O3-δ (SZYO) with a perovskite structure were deposited on (111)Pt//(111)SrTiO3 (STO) single crystal substrates by an RF-magnetron sputtering method. X-ray diffraction revealed that the BCYO and SZYO thin films were polycrystalline but highly (110)-one-axis oriented with local epitaxy on (111)Pt//(111)STO in the 〈110〉-direction. However, these films have six-fold symmetric domains and each domain showed in-plane rotations because of the lattice mismatches between (110)BCYO or (110)SZYO and (111)Pt. Especially, the BCYO film showed larger in-plane rotation than that of SZYO because of its larger lattice mismatch.

Thermal diffusion and epitaxial growth of Ag in Ag/SiO2/Si probed by XRD, depth-resolved XPS, and slow positron beam

Ag/SiO2/Si multilayer samples with different SiO2 layer thicknesses were prepared through deposition of Ag layer onto SiO2/Si substrates at different substrate temperatures (Tsub) by RF magnetron sputtering method. Microstructure of the multilayer was characterized by XRD θ/2θ scan and φ-scan analysis, depth-resolved XPS analysis, and Doppler broadening of annihilation radiation (DBAR) spectra of positron measurements. The experimental results indicate that, at Tsub = 25 °C, the Ag deposition forms Ag/SiO2/Si multilayer structure. With Tsub increasing to 200 °C, Ag atoms are found to diffuse into the SiO2 layer. This thermal diffusion process plays a critical role in removing SiO2 layer on the Si substrate. At Tsub of 600 °C, the 31-nm-thick SiO2 layer is partially desorbed from the Si surface as a result of Ag diffusion, and eventually results in a deposition of Ag layer directly on the Si substrate. This is also confirmed by the XRD φ-scan measurements, which indicates epitaxial growth of Ag atoms directly on the surface of Si substrate at Tsub of 600 °C.

Influence of RF sputtering power and thickness on structural and optical properties of NiO thin films

NiO thin films were deposited by RF magnetron sputtering method under 3–4 sccm O2 (99.99%) in the O2/Ar + O2 flow rate at 450 °C substrate temperature at different RF powers and different thicknesses. The structural properties of NiO thin films were investigated using atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray Photoelectron Spectroscopy (XPS). The optical properties were studied by UV–vis spectroscopy and photoluminescence (PL) at room temperature. AFM studies show that the roughness parameters of the NiO surfaces are influenced by the film thickness and sputtering RF power. The XRD results revealed that as-prepared NiO films are polycrystalline and developed [111] preferred orientation. XPS study confirmed the presence of Ni2+ and Ni3+ ions in the NiO films. In the case of varying the thickness of the films at 210 W RF power, the optical band gap (Eg) values are 3.48 eV for 150 nm and 200 nm. For NiO films with 250 nm, 300 nm and 350 nm thicknesses, the Eg vary between 3.43 and 3.45 eV. PL spectra of the NiO thin films show bands emission in UV–vis region, which are affected by RF sputtering power.

Preparation of rare-earth thulium doped tin-oxide thin films and their applications in thin film transistors

Tm3+ doped SnO2 semiconductor thin films were prepared by RF magnetron sputtering method. The doping effects of rare-earth thulium on the crystal structures, optical properties, chemical compositions, surface morphologies of tin-oxide thin films, together with the electrical properties of the corresponding SnTmO thin film transistors (TFTs), were investigated. SnTmO semiconductor thin films with polycrystalline structures feature a wide bandgap of over 3.8 eV. XPS results reveal the typical photoelectron signals of Sn4+ and Tm3+. Smaller crystallite size and more grain boundaries can be formed in doped SnO2 samples which may be responsible for the degradation of device mobility. It was found that the electrical properties of SnO2 TFTs can be modulated by Tm3+ incorporation. The appropriate Tm3+ doping concentration is around 1.6 at.% within our experimental conditions. The optimized field-effect mobility, subthreshold swing, threshold voltage, on-off current ratio and the interface trap density are 5.5 cm2 V−1 s−1, 0.618 Vdec−1, −2.3 V, 5 × 107 and 6.7 × 1011 cm−2, respectively. Stability measurements show threshold voltage shifts of 12.3 V and −11.7 V in PBS and NBS process respectively. This study may provide useful understandings on rare-earth doped SnO2 semiconductors.

Electrical Parameters of the Erbium Oxide MOS Capacitor for Different Frequencies

Electrical parameters of Erbium Oxide (Er2O3) MOS capacitors depending on frequency were investigated deeply, in this paper. Er2O3 layers were deposited on p–Si substrates with (100) oriented using RF–magnetron sputtering method. The films were annealed at 500 oC in N2 environment. C–V characteristic changes reduce with increasing frequency. G/ω–V characteristic variations show different behavior between 10–250 kHz and 250 kHz–1 MHz. It is thought that these different behaviors are caused by interface states between silicon and Er2O3 layer, series resistance (Rs) effects and the relaxation time of trapped states. The Rs values calculated by the Cma and Gma values at the high frequency and decrease with rising frequency. Then, Cc­­–V and Gc/ω–V characteristic curves were measured and compared to first measurements. In addition, interface state density (Dit), diffusion potential (VD), and barrier height (B) were calculated and these results demonstrate similar behaviors.

Improving the production of high-performance solar-blind β-Ga2O3 photodetectors by controlling the growth pressure

In this work, β-Ga2O3 films are obtained by the RF magnetron sputtering method. Effects of the growth pressure on properties of the deposited β-Ga2O3 films and the corresponding solar-blind metal–semiconductor–metal photodetectors are investigated systematically. It is shown that when the deposition pressure increases, the full width at half maximum of β-Ga2O3 $$ \left( {\bar{2}01} \right) $$ X-ray diffraction peaks decreases firstly and then increase. The peak intensities increase firstly, reach a maximum at 25 mTorr and then decrease with increasing pressure. The similar variation tendency is also reflected on the bandgap, oxygen vacancy and roughness of β-Ga2O3 films. It is supposed that all these properties depend on two factors: atoms diffusion ability and the defects with growth pressure. By controlling the growth pressure, the fabricated interdigitated solar-blind photodetectors exhibit excellent characteristics, including a large spectral responsivity (303 A/W), a low dark current (10pA at 20 V), a large photo-to-dark current ratio (> 105), a high external quantum efficiency (over 1 × 105%) and a fast response speed (rise time: 0.52 s and fall time: 0.12 s).

Swift heavy ion irradiation assisted Si nanoparticle formation in HfSiOx nano-composite thin films deposited by RF magnetron sputtering method

Silicon co-deposited HfOx thin films were prepared by RF magnetron sputtering method. The average size of Si co-deposited nanocomposites is around 10–12 nm. 100 MeV Ag ion irradiation induces the Si nano-crystal formation within the nanocomposite. The average grain size of the Si nano-crystals increases with the increase of ion fluence. The observed luminescence at 430 nm is due to oxygen related defect states and the luminescence at 530 nm may be attributed to the emission from Si nanoparticles. Red shift in emission wavelength indicates either the increase in the size of the nanoparticles or ion induced change in the dielectric constant of surrounding medium. The increase in the intensity of the luminescence peak at 440 nm indicates the creation of defect states by ion irradiation. Raman measurements further confirm the formation of Si NPs that are embedded in the composite medium.

Influence of heat treatment of the base material on the electrical properties of anisotyped heterojunctions n-ZnO:Al/p-CdZnTe

The conditions for the production of rectifying anisotyped heterostructures ZnO:Al/p-Cd1-xZnxTe by the method of RF-magnetron sputtering of ZnO:Al films onto crystalline substrates p-Cd1-xZnxTe were investigated. High energy parameters of the barrier were realized by preliminary heat treatment of the substrates. Mechanisms of forming direct and reverse currents through the heterojunction were set based on the analysis of temperature dependences of I–V-characteristics. Based on the researches of C–V-characteristics, the interconnection between physical processes during heat treatment was established, which makes possible to avoid the negative influence of the differences between crystalline materials lattices on the heterojunctions. Suggested models of energy diagrams of the manufactured heterostructures are well describe experimental electrophysical phenomena.

Temperature dependence of band gaps in sputtered SnSe thin films

Temperature-dependent transmission experiments were performed for tin selenide (SnSe) thin films deposited by rf magnetron sputtering method in between 10 and 300 K and in the wavelength region of 400–1000 nm. Transmission spectra exhibited sharp decrease near the absorption edge around 900 nm. The transmittance spectra were analyzed using Tauc relation and first derivative spectroscopy techniques to get band gap energy of the SnSe thin films. Both of the applied methods resulted in existence of two band gaps with energies around 1.34 and 1.56 eV. The origin of these band gaps was investigated and it was assigned to the splitting of valence band into two bands due to spin-orbit interaction. Alteration of these band gap values due to varying sample temperature of the thin films were also explored in the study. It was seen that the gap energy values increased almost linearly with decreasing temperature as expected according to theoretical knowledge.

Transparent and Conducting Oxide Films: SiO₂-Doped ZnO.

(SiO₂)x(ZnO)100-x films with x = 2, 3, 4, and 5 wt.% were deposited on slide glass substrates at room temperature by the conventional Rf magnetron sputtering method. Their resistivities were investigated as a function of SiO₂ content. The lowest resistivity of 4.5×10-3 Ω.· cm was obtained for the (SiO₂)x(ZnO)100-x film with x = 2 wt.%. This film showed an excellent average transmittance of 85% in the visible range with a wide band gap over 3.4 eV and a high refractive index of 2.1. In addition, the electrical conductivity of the films was improved by annealing at a temperature films decrease range from 100 °C to 400 °C in vacuum. The resistivities of (SiO₂)x(ZnO)100-x with increasing annealing temperature. In particular, SZO film with x = 2 wt.% shows a minimum resistivity of ~10-3 Ω.cm after the heat treatment for 30 min at 300 °C in vacuum. Thus, we suggest that (SiO₂)x(ZnO)100-x films being sufficiently transparent and having a high conductivity, are suitable for application as transparent and conductive oxide films.

Crystal growth of a MnS buffer layer for non-polar AlN on Si (100) deposited by radio frequency magnetron sputtering

The growth conditions of MnS thin film on a Si (100) substrate deposited by the RF-magnetron sputtering method were investigated. The MnS is a buffer layer for the epitaxial growth of non-polar AlN thin film on the Si (100) substrate. The 4°-off-Si (100) substrate and the insertion of MnS film grown at room temperature (RT-MnS) improved the crystallinity and the surface roughness of the MnS film. In particular, the 20 nm thick RT-MnS showed a reduction of surface roughness of the MnS layer deposited at 550 °C. The root mean square value of the MnS layer was 0.23 nm, which is in the same range as that of the Si substrate. X-ray photoelectron spectroscopy measurements revealed that RT-MnS insertion with a thickness over 10 nm reduced the sulfur vacancy formation in the MnS film deposited on RT-MnS, and the MnS was thermally stable at the growth temperature of AlN.

Effects of La-doping on piezoelectricity properties of 0.15BiInO3-0.85PbTiO3 thin films deposited by RF magnetron sputtering method

La-doped 0.15BiInO3-0.85PbTiO3 thin films are deposited on SRO/Pt/MgO substrates by RF-magnetron sputtering method. The structures of the thin films are characterized by XRD and AFM. Meanwhile, the effects of La doping concentrations on the piezoelectricity of the films are measured. At the same time, the transverse piezoelectric coefficients of the films are simulated by COMSOL combined with CASTEP calculations. The simulated results are in agreement with the experimental data, which show that the La-doping 0.15BiInO3-0.85PbTiO3 films have optimized properties by properly controlling the La doping compositions. It is found that the effective transverse piezoelectric coefficients have a maximum of -9.35 C/m2 as 3 mol.% La-doping 0.15BiInO3-0.85PbTiO3 films.

Structural, Optical and Electrochromic Property of WO3: MoO3 Thin Film Prepared by RF Magnetron Sputtering Technique

Tungsten oxide (WO3) films have been deposited on glass substrates by RF magnetron sputtering method for different MoO3 concentration. During experiment consternation of MoO3 was varied from 5%, 10% and 15%. We examined the effect of various MoO3 concentration on structural, optical and electrochromic properties of WO3 films. To study, crystal structure and other properties XRD analysis carried out, and we found that the deposited films shows amorphous feature. The optical properties were examined using UV–Visible spectrophotometer using wavelength range 300-900 nm. From the transmittance spectra we found that as the concentration of MoO3 increases the band gap and transmittance value decreases. The electrochromic properties were examined using three electrode electrochemical cell and the potential applied between ±2.2 V. After studying electrochromic property we observed that WO3:MoO3 the films have good coloration and bleaching properties and the maximum value for coloration efficiency was 2.303 mm2/C for 15% MoO3 concentration.

A novel and facile way to fabricate transparent superhydrophobic film on glass with self-cleaning and stability

Transparency is one of the most important properties of superhydrophobic (SHP) surface applied on outdoor solar cells and other outdoor windows. In this work, transparent SHP ZnO surface was fabricated via RF magnetron sputtering method. The effect of film thickness and surface roughness on the wettability and optical property of the as-prepared surfaces were investigated. Results show that the as-prepared SHP ZnO surface with sputtering time of 2 min exhibits excellent self-cleaning property and stability against corrosive rain, various environmental temperatures and impacting water droplet with high velocity. The fabrication process is stable and easy to control, which can largely widen the applications of the as-prepared transparent SHP surfaces.

High Ferroelectricities and High Curie Temperature of BiInO3PbTiO3 Thin Films Deposited by RF Magnetron Sputtering Method☆☆Supported by the National Natural Science Foundation of China under Grant No 11304160, the Special Fund for Public Interest of China under Grant No 201510068, and the NUPTFC under Grant No NY215111.

Properties of ferroelectric xBiInO3-(1 − x)PbTiO3 (xBI-(1 − x)PT) thin films deposited on (101) SrRuO3/(200) Pt/(200) MgO substrates by rf magnetron sputtering method and effects of deposition conditions are investigated. The structures of the xBI-(1 − x)PT films are characterized by x-ray diffraction and scanning electron microscopy. The results indicate that the thin films are grown with mainly (001) orientation. The chemical compositions of the films are analyzed by scanning electron probe and the results indicate that the loss phenomena of Pb and Bi elements depend on the pressure and temperature during the sputtering process. The sputtering parameters including target composition, substrate temperature, and gas pressure are adjusted to obtain optimum sputtering conditions. To decrease leakage currents, 2 mol% La2O3 is doped in the targets. The P–E hysteresis loops show that the optimized xBI-(1 − x)PT (x = 0.24) film has high ferroelectricities with remnant polarization and coercive electric field . The Curie temperature is about 640 °C. The results show that the films have optimum performance and will have wide applications.

Investigation of the electrical and optical properties of nickel oxide films produced by RF magnetron sputtering method

Nickel oxide (NiO) thin films were deposited by an RF magnetron sputtering process in different atmospheres: one with a mixture of nitrogen and argon, and another with oxygen and argon. The structural, optical and electrical properties of NiO films were investigated using the spectroscopy, atomic-force microscopy and resistivity measurements. The dependencies of the film properties on atmosphere composition were studied. Optimization of the NiO thin film properties was carried out for further fabrication of effective hole transport layers for perovskite solar cells.

Structural, Thermal and Luminescence Properties of AlN:Tm Thin Films Deposited on Silicon Substrate and Optical Fiber

Thin films of AlN:Tm are deposited on a Si(111) and Si(100) substrates and optical fiber by rf magnetron sputtering method. 200–400 nm thick films are deposited at various temperatures to observe the effect of temperature on their structure and morphology. Liquid nitrogen is used to deposit films at low temperature of –196°C. An electric heater is used to grow films at 250–700°C range. The deposited films are analyzed for their structure and thermal stability using X-ray diffraction and thermogravimetric analysis. Films deposited at liquid nitrogen temperature are amorphous and those deposited at high temperature are crystalline. Average grain size, strain and interatomic distance of the crystalline films are calculated. The grain size and inter-atomic distance increase from 36.54 to 45.12 nm and from 0.2368 to 0.25 nm respectively. Photoluminescence of the films excited by 783 nm crystal laser shows an intense infrared emission from Tm+3 at 802 nm as a result of 3H4 → 3H6 transition.

Transparent ITiO film electrodes on polyethylene terephthalate by oxygen plasma treatment for high-performance flexible electroluminescence device

A plastic electrode transparent is important to flexible optoelectronic devices. The metal oxides are coated in plastic by a variety of methods. The temperature in the process will not exceed 100 °C–150 °C or room temperature. It causes cracking on the film, adhesion on the plastic surface, and impurities on the film. Therefore, plasma oxygen was used to improve the film. In this work, we fabricate plastic electrode transparent with indium titanium oxide (ITiO) film using oxygen (O2) plasma treatment. ITiO film was deposited on polyethylene terephthalate (PET) using the RF magnetron sputtering method. The obtained ITiO PET films were plasma treated with O2 using the plasma enhanced chemical vapor deposition system at plasma power and plasma treatment time condition. The structural properties and crystalline of ITiO film were confirmed by X-ray diffraction by scanning electron microscope and atomic force microscope. The high transmittance of ITiO films was about 80%–86% of all plasma treatment conditions. The lowest resistivity of the ITiO films with plasma treatment by plasma power condition and plasma treatment time was 7.92 × 10–1 Ω-cm of 300 W plasma power and 7.81 × 10−1 Ω-cm of 300 W plasma power, respectively. The luminance properties and EL efficiency of ITiO PET film was 89.21 cd m−2 and 0.0365 lm W−1 for a 60 min treatment time, 72.42 cd m−2 and 0.0297 lm W−1 for plasma power. The use of ITiO on a PET film by oxygen plasma treatment can improve the performance of the display device.

Plasmonic Ag nanowires sensitized ZnO flake-like structures as a potential photoanode material for enhanced visible light water splitting activity

Silver nanowires (AgNWs) functionalized ZnO flake-like (ZnO/AgNWs) morphological heterostructures were developed as a promising photoanode by facile RF magnetron sputtering and polyol methods. Herein, we demonstrate the role of rationally tailored AgNWs weight concentration (0, 0.03, 0.05 and 0.07g) on ZnO flake-like morphology for enhanced visible-light-driven photoelectrochemical (PEC) water splitting activity. From XRD studies, ZnO (002) facets were effectively influenced by the selective growth of Ag (111) facets. Notably, XPS studies reveal the strong correlation between AgNWs and ZnO, showing a significant red shift in Zn 2p and O 1s levels and blue shift in Ag 3d level. Whereas, surface hydroxyl groups (OH−) were originated on ZnO/AgNWs heterostructure, which acts as light trapping states. Interestingly, FESEM images comprise AgNWs distribution on ZnO flake-like morphology, which suggests AgNWs are most accessible networks at the interface of ZnO. As a result, we observed significant variation in the optical transmittance and matching band gap for strong visible light absorption. In conclusion, selective growth of AgNWs-0.05g on ZnO promoted the strong interface reaction kinetics with impressive photoconversion efficiency (0.38%). Thus, developing of unique flake-like/nanowire morphological features underlined to be crucial interest in energy conversion applications.