Facing Targets Sputtering Method Research Articles

Effect of annealing treatment of indium tin oxide thin films on film properties and transparent antenna properties

There is a growing demand for transparent thin film antennas to serve as access points for wireless communication that can be installed at any location without compromising visibility, while retaining the versatility of existing antennas. Although studies exist on indium tin oxide (ITO)-based transparent antennas, studies on the effect of thin-film process parameters on antenna properties are rare. In this study, we deposited ITO, which resonates at 3.3 GHz, using the facing target sputtering method with different thicknesses ranging from 400 to 2000 nm, from a typical thin film to a relatively thick film. ITO thin films deposited at room temperature were annealed in air at 200, 300, and 400 °C in an electric furnace. The optically transparent monopole antennas were fabricated using air-annealed ITO films. The effects of the annealing temperature on the film and antenna properties were investigated. A high radiation efficiency of 70.8 % was achieved while maintaining a transmittance of more than 70 % for a 2000 nm ITO film annealed at 400 °C. The results indicate that tailoring appropriate conductive film properties for desired transmittance is crucial to realize the expected antenna performance.

Interfacial roughness driven manipulation of magnetic anisotropy and coercivity in ultrathin thulium iron garnet films

We have investigated the magnetic properties of thulium iron garnet (Tm3Fe5O12, TmIG) thin films grown on {111} gadolinium gallium garnet (Gd3Ga5O12, GGG) substrates fabricated via the facing target sputtering method. The annealing temperature (Ta), thickness (tf), and roughness were systematically controlled in order to obtain the perfect magnetic properties of the film showing perpendicular magnetic anisotropy (PMA) and large coercive field, which are the requisites for non-volatile magnetic memory device applications. Here, we demonstrated that the Ta acts as the crucial parameter both for obtaining the high quality of the film surface and engineering the direction of the magnetic anisotropy from the in-plane to out-of-plane. Through the further optimization process with a function of the tf, we successfully achieved the best condition for the PMA films. Specifically, the sample fabricated at a tf of ≤ 20 nm and Ta of 1000 ℃ showed the perfect PMA. Furthermore, the surface roughness of the substrate mainly contributes to the enhancement of the coercive field of the perpendicular magnetic anisotropic films. We speculate that the drag force from the pinning energy induced by the interfacial roughness retarded the domain wall motion at the TmIG/GGG interface, resulting in enhanced coercivity.

Photoluminescence of Amorphous Carbon Nitride (a-C:N) thin Films Grown by Facing Target Sputtering Method

Photoluminescence of Amorphous Carbon Nitride (a-C:N) thin Films Grown by Facing Target Sputtering Method

Top-emission organic light emitting diode with indium tin oxide top-electrode films deposited by a low-damage facing-target type sputtering method

To confirm the effectiveness of the low-damage facing-target sputtering (FTS) method for the deposition of a transparent oxide electrode film on an organic layer, an indium tin oxide (ITO) top electrode was deposited via FTS, and a top emission organic light-emitting diode (OLED) was fabricated. Top and bottom electrode films were deposited using the FTS system; in addition, a top emission a bottom emission OLED were fabricated with an inverse stacking structure. Consequently, both OLEDs exhibited similar operating characteristics, and the top emission OLED had a better luminance efficiency than the bottom emission OLED did. Compared with the OLED fabricated using the evaporation method, the OLEDs fabricated using FTS exhibited similar luminance efficiencies, although they had considerably higher operating voltages. In addition, annealing treatment at 110 °C was observed to lead to a significant reduction in the operating voltages; moreover, the obtained top emission OLEDs exhibited operating characteristics similar to those of the OLED fabricated using the evaporation method. These results indicate that the FTS method is useful for the deposition of the top oxide electrode films of OLEDs.

Effects of Electron Beam Treatment on Amorphous Carbon Nitride Thin Films Grown by Using the Facing Target Sputtering Method

Effects of Electron Beam Treatment on Amorphous Carbon Nitride Thin Films Grown by Using the Facing Target Sputtering Method

Color Controls of TiO$_2$ Thin Films Grown on Half-Mirrored Stainless-Steel Substrates by Using the Facing Target Sputtering Method

Color Controls of TiO$_2$ Thin Films Grown on Half-Mirrored Stainless-Steel Substrates by Using the Facing Target Sputtering Method

Effect of IZO passivation layer on AgNWs flexible transparent electrode

ABSTRACTIn this paper, we report the fabrication of flexible transparent electrodes using silver nanowires (AgNWs) as the main material, and an indium zinc oxide (IZO) thin film as a passivation layer to protect the AgNWs. The AgNWs were deposited on glass and polyethersulfone (PES) substrates by a spin coating method, and IZO films were deposited on the AgNWs by a facing targets sputtering (FTS) method. The FTS system used in this study is made up of two targets that face each other. This can minimize the substrate damage from the high-energy sputtered particles and plasma particles, improving the device characteristics. In order to check the effectiveness of IZO as a passivation layer, we performed an adhesion test and an oxidation test. The results confirmed that the IZO thin film enhances the adhesiveness of the substrate with AgNWs and prevents the oxidation of the substrate by atmospheric oxygen. The IZO/AgNWs structures deposited on the PES substrates showed excellent properties in extreme bending tests, which determine the flexibility for small or thin device fabrication. Measurements of the electrical and optical properties of the samples confirmed a sheet resistance of 10 Ω/sq. and a transparency of 93%, at 1 time of AgNWs coating. Thus, IZO thin films were fabricated by the FTS method as a passivation layer that protects the AgNWs to form IZO/AgNWs structures that can be used as flexible transparent electrodes.

Characterization of ZTO Thin Films Transistor Deposited by On-axis Sputtering and Facing Target Sputtering(FTS)

We have investigated the properties of thin film transistors(TFT) fabricated using zinc tin oxide(ZTO) thin films deposited via on-axis sputtering and FTS methods. ZTO thin films deposited by FTS showed lower root-mean-square(RMS) roughness and more uniformity than those deposited via on-axis sputtering. We observed enhanced electrical properties of ZTO TFT deposited via FTS. The ZTO films were deposited at room temperature via on-axis sputtering and FTS. The as-deposited ZTO films were annealed at 400 °C. The TFT using the ZTO films deposited via FTS process exhibited a high mobility of 12.91 cm2/V.s, a low swing of 0.80 V/decade, Vth of 5.78 V, and a high Ion/off ratio of 2.52 × 106.

Large-area thin-film capacitors deposited onto graphene bottom electrodes via facing-target sputtering that is free of plasma damage

One hundred nm-thick Bi2Mg2/3Nb4/3O7 (BMN) thin films were deposited onto graphene bottom electrodes at 300 °C via on-axis sputtering and facing-target sputtering (FTS) to produce 4 × 4 cm2 capacitors. The graphene films grown on Ni (250 nm)/Si (001) via rapid-thermal chemical vapor deposition (RTP CVD) were transferred to Ti (10 nm)/SiO2 (250 nm)/Si (001) substrates for removal of the wrinkles and ripples. The on-axis sputtering deteriorated the dielectric and leakage current properties of the BMN capacitors. The FTS method was free of plasma damage, which remarkably enhanced the electrical properties of the BMN/graphene thin-film capacitors. FTS is an attractive method for large-scale thin-film capacitors that use graphene bottom electrodes.

Anomalous Hall effect in Co40Fe40B20/SiO2/Si structures

Co40Fe40B20/SiO2/Si structures fabricated by a facing-target sputtering method exhibit anomalous Hall effect. The longitudinal resistance shows a metal-insulator transition with the increase of temperature. The Hall resistance first increases, and then decreases with the increase of temperature. The character of Hall loops undergoes a crossover from AHE to ordinary Hall effect with the increase of temperature. Such electronic transport properties can be understood by a two current channels model. On the other hand, the critical saturated magnetic field of Hall loops drops rapidly at 350 K, which can be attributed to the reduction of spin-polarized carriers in Co40Fe40B20.

有機 EL 素子作製のための低ダメージスパッタ堆積法の開発

Deposition of top Al electrode films by a low damage Facing-Target sputtering method (FTS) have been attempted to fabricate an Organic Light Emitting Diode (OLED) (glass substrate/ITO /NPB/Alq3/BCP/LiF/Al). Suppression of the high energy secondary electron incidence to the substrate during the sputter-deposition of the aluminum electrode films was effective to reduce the light emitting voltage and improve the luminance efficiency of the OLED. In addition, optimization of sputtering gas pressure and reduction of the sputtering current was necessary in the deposition the electrode films to obtain the OLED with good performance. Compared with the OLED fabricated by vacuum evaporation, the OLED fabricated by our low damage sputtering system at the optimum conditions showed better injection current-luminance efficiency, although it had a little bit larger operating voltage.

Properties of Silver Nanowire/Zinc Oxide Transparent Bilayer Thin Films for Optoelectronic Applications

We have investigated electrical, optical and structural properties of silver nanowire (AgNW)/zinc oxide (ZnO) transparent conductive bilayer films for optoelectronic applications. The AgNW/ZnO transparent conductive bilayer films were fabricated using spin-coating and facing target sputtering (FTS) method. The spin-coated the AgNW layer has advantages, such as low resistivity and high transmittance in visible range. However, the spin-coated AgNW layers can be oxidized by natural oxygen. Consequently, the conductivity of AgNW layer was strongly decreased. So, an oxidation prevented layer is necessary. The ZnO thin film layer on the Ag NW layer can be prevented oxidation. In addition, the peeling of spin-coated AgNW layer were prevented the deposited ZnO thin film layer. As the results, the sheet resistance and average transmittance in visible range of AgNW/ZnO transparent bilayer thin films exhibited 34.1 ohm/sq. and 83.46%.

Reactive Sputtering of Plasmonic Pt/ZnO Films for Decomposition of Gas-Phase Methanol under Visible Light.

The preparation of ZnO films by a versatile and effective facing-target sputtering method under various sputtering pressures is described. The ZnO films are coated with an ultrathin (2 nm) Pt layer through dc diode sputtering to form hybrid Pt/ZnO photocatalytic films. Interestingly, the Pt/ZnO films show an efficient visible-light photoresponse for the decomposition of gas-phase methanol owing to the unique surface plasmon resonance of the Pt film.

A potentiometric immunosensor based on a ZnO field-effect transistor

The characteristics of an aptamer-modified Ta2O5/ZnO field-effect transistor as a prototype label-free immunosensor for the potentiometric electrical detection of immunoglobulin G (IgG) were studied. The Ta2O5/ZnO film was grown on a glass substrate by a facing-target sputtering method. Stable operation in electrolyte solution with a small hysteresis width and a low gate leakage current was realized. The immunosensor exhibited a proportional sensitivity to the logarithmic human IgG concentration in the range of 0.35–23 µmol·dm−3 with a rapid response time of ∼15 s.

Full-Heusler Co2FeSi alloy thin films with perpendicular magnetic anisotropy induced by MgO-interfaces

A 100-nm-thick L21-ordered full-Heusler Co2FeSi (CFS) alloy film was fabricated using the facing targets sputtering (FTS) method at a substrate temperature TS of 300 °C. The degrees of L21- and B2-order for the film were 37% and 96%, respectively. In addition, full-Heusler CFS alloy thin films with perpendicular magnetic anisotropy (PMA) induced by the magnetic anisotropy of MgO-interfaces were also successfully fabricated using the FTS method. The CFS/MgO stacked layers exhibited PMA when the CFS layer had a thickness of 0.6 nm ≤ dCFS ≤ 1.0 nm. The PMA in these structures resulted from the CFS/MgO interfacial perpendicular magnetic anisotropy.

Characteristics of Ga-Al Doped ZnO Thin Films with Plasma Treatment Prepared by Using Facing Target Sputtering Method

Ga-Al-doped ZnO (GAZO) thin films were prepared on glass substrates using facing targets sputtering at room temperature. GAZO thin films have been treated in O2 plasma to modify surface roughness in order to enhance the efficiency of OLED anodes made from the films. After deposition of the thin films, the substrate was subjected to plasma surface treatment. The electrical, optical, and surface properties of the deposited thin films were investigated by hall-effect measurement, UV/Vis spectrometry, and atomic force microscopy (AFM), respectively. As a result of increasing the plasma treatment time from 0 to 45 sec, the surface roughness of films after plasma treatment was improved, but their electrical, optical, and structural properties were slightly changed. The lowest values of the surface roughness were 1.409 nm for the as-deposited GAZO thin films for an O2 plasma treatment time of 40 sec. All GAZO thin films have an average transmittance of 90% in the visible range (400-800 nm).

Electrochromic Properties of Tungsten Oxide Films Prepared by Reactive Sputtering

WO3-x thin films were deposited on induim tin oxide (ITO) glass substrates with various oxygen flow ratios from 0.55 to 0.7 by the reactive facing-target sputtering method, at a power density of 4 W/cm2 and room temperature. The structural properties of the WO3-x thin films were measured by X-ray diffractometry and Raman spectral analysis. As-deposited WO3-x thin films had an amorphous structure. In the Raman spectra, WO3-x thin films exhibited two strong peaks at 770 and 950 cm-1 attributed to the vibrations of W6+–O and W6+=O bonds, respectively. The electrochemical and optical properties of WO3-x thin films were measured by cyclic voltammetry and UV/vis spectrometry. The results showed the highest charge density at an oxygen flow ratio of 0.7 and the highest transmittance in the visible range. The maximum coloration efficiency was 30.82 cm2/C at an oxygen flow ratio of 0.7.

Properties of AZO/Ag/AZO Multilayer Thin Film Deposited on Polyethersulfone Substrate

The AZO/Ag/AZO multilayer films were deposited on polyethersulfone (PES) substrate by using facing target sputtering methods at room temperature. The AZO/Ag/AZO multilayer films with polymer substrate had advantages, such as low sheet resistance, high optical transmittance in visible range and stable mechanical properties. From the results, the AZO/Ag/AZO multilayer films (50/12/50 nm) demonstrated a sheet resistance of 11 Ω/□ and average transmittance of 87% in visible range (wavelength of 380-770 nm). Moreover, the multilayer showed stable mechanical properties compared to the single-layered AZO sample during the bending test due to the existence of the ductile Ag metal layer.

Design of antireflective coatings for AZO low infrared emissivity layer

In this letter, we investigate the structural, optical, and electrical properties of Al-doped ZnO (AZO) thin film coating prepared by direct current (DC) facing-target sputtering method at room temperature, of which the average optical transmittance is 81% between 400 and 700 nm while the sheet resistance is about 10 \Omega/. Then, based on this AZO coating, in order to enhance the transmittance, interfacial adhesion strength and weathering resistance, two kinds of antireflective coatings are designed for different application purposes. For the two kinds, the highest transmittances in the visible region (400–700 nm) can reach 86.9% and 81.8%, respectively. The design is performed using Macleod Optical Design software.

Properties of Ga-Al Doped ZnO with Various Thicknesses Prepared by Facing Targets Sputtering Method

Gallium-Aluminum doped Zinc Oxide (Ga-Al doped ZnO) thin films prepared on glass substrates by using facing targets sputtering methods. Electrical, structural and optical properties of Ga-Al doped ZnO thin film with various thicknesses were studied in detail. Crystal structure of the Ga-Al doped films was hexagonal wurtzite. Increased thickness of Ga-Al doped ZnO thin film, the resistivity decreased and crystallity improved. As the results, The resistivity of Ga-Al doped ZnO thin films with thickness of 500 nm exhibited 4.17×10–4 Ω.cm and average optical transmittance of all thin films showed above 85% in the visible range.