Radio-frequency Magnetron Sputtering Deposition Method Research Articles

The ferroelectric and piezoelectric properties of (Hf1−x Ce x )O2 films on indium tin oxide/Pt/TiO x /SiO2/(100)Si substrates obtained using a no-heating radio-frequency magnetron sputtering deposition method

The effect of composition and film thickness on the ferroelectric and piezoelectric properties of (Hf1−x Ce x )O2 films deposited without substrate heating was investigated. (Hf1−x Ce x )O2 films with various x values (x = 0.07–0.27) and thickness (150–880 nm) were deposited via RF magnetron sputtering on indium tin oxide (ITO)/Pt/TiO x /SiO2/(100)Si substrates. The crystalline phases of the films were observed by X-ray diffraction. The measurements of electrical properties revealed ferroelectric phases in the x range of 0.11–0.21. The film with x = 0.16 exhibited the maximum remanent polarization (Pr) of 15 μC cm−2, as well as the highest effective piezoelectric coefficient. In addition, the ferroelectric and structural properties remained almost unchanged with increasing film thickness. Therefore, the no-heating deposition of ferroelectric (Hf1−x Ce x )O2 films and their phase stability with respect to thickness were demonstrated in this study. This work provides a pathway for the deposition of ferroelectric (Hf1−x Ce x )O2 films on flexible, wearable sensors.

Self-Flattened ZnO:Al Transparent Conductive Thin Films Derived by Sol–Gel Process

Self-flattened and low-resistance Al-doped ZnO (ZnO:Al) thin films were developed by sol-gel process, for providing a versatile transparent conducting oxide material that enables the growth of high-quality photoactive layers and enhancement in light absorption by intensifying light-scattering simutaneously. The electrical, optical, and structural characteristics of the sol-gel derived ZnO:Al thin film was evaluated by comparing with the B-doped ZnO (ZnO:B) fabricated by the metalorganic chemical vapor deposition method and ZnO:Al fabricated by the radio-frequency magnetron sputtering deposition method. This sol-gel derived ZnO:Al thin film shows the c-axis oriented wurtzite structure, a resistivity of 9.89 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> Ω·cm, and smoother surface morphology and larger figure of merit σ/ α than the vacuum-technique derived ZnO thin film with similar thickness. This low resistivity was achieved by optimizing the Al doping concentration and annealing process. Employed as the front electrode, it enabled a better device performance of hydrogenated amorphous Si single-junction solar cells with respect to the ZnO:B thin film with similar thickness by improving the Voc and fill factor (FF). The dark J-V characteristics of these devices were analyzed to investigate the mechanism of Voc and FF improvement. These results suggest a promising candidate for the transparent electrode of superstrate-type thin-film solar cells.

Development of dye-sensitized solar cells based on visible-light-responsive TiO2 thin films with a unique columnar structure

A visible-light-responsive TiO2 thin film (Vis-TiO2), possessing a unique columnar structure oriented perpendicular to the substrate, has been prepared by using a radio-frequency magnetron sputtering deposition method. The unique TiO2 thin film was used as a key component of N719 dye-sensitized solar cells (DSSCs). The rough morphology caused by the columnar structure leads to enhanced photovoltaic performances of these DSSCs as a consequence of increased amounts of adsorbed dyes and facilitated diffusion of the electrolyte into Vis-TiO2 film. Additionally, photovoltaic performances of the DSSCs were found to depend strongly on the thickness of the Vis-TiO2 film, which can be readily controlled by adjusting the sputtering time conducted for deposition. Consequently, a solar-to-electric energy conversion efficiency of 2.6 % under AM 1.5 illumination was observed for an optimally performing DSSC that has a Vis-TiO2 film thickness of 6.9 μm, prepared by employing a sputtering time of 700 min.

Effect of the sputtering parameters on the physical properties and photocatalytic reactivity of TiO2 thin films prepared by an RF magnetron sputtering deposition method

Visible light-responsive TiO2 (Vis-TiO2) thin films were successfully developed by applying a radio-frequency magnetron sputtering deposition method by controlling various sputtering parameters such as the substrate temperature, Ar gas pressure, and the target-to-substrate distance. UV–Vis, XRD and SEM investigations revealed that optical property, the crystal structure, and photocatalytic activity of Vis-TiO2 are strongly affected by the sputtering parameters during the deposition step. Vis-TiO2 was found to act as an efficient photocatalyst for the H2 and O2 evolution from water under visible light irradiation (λ ≥ 420 nm). SIMS investigations have revealed that a slight decrease in the O/Ti ratio of the TiO2 thin films plays an important role in the modification of the electronic properties of Vis-TiO2 thin films, enabling them to absorb visible light.

Photocatalytic oxidation of 2-propanol under visible light irradiation on TiO2 thin films prepared by an RF magnetron sputtering deposition method

Visible light-responsive TiO2 (Vis-TiO2) thin films able to absorb UV and visible light in wavelength regions of 250-600 nm were successfully developed by applying a radio-frequency magnetron sputtering deposition method. These Vis- TiO2 thin films exhibited high activity for the photocatalytic oxidation of 2-propanol diluted in water even under visible light irradiation (k C 450 nm). The photocata- lytic activity of Vis-TiO2 thin films was dramatically enhanced by the deposition of Pt particles on the surface. Secondary ion mass spectrometry measurements revealed that Pt particles are distributed from the top surface to the deep bulk of Vis- TiO2 thin films with a columnar structure. The unique columnar structure of Vis- TiO2 thin films plays an important role in the high photocatalytic performance.

Photocatalytic activity of visible light-responsive TiO2 thin films deposited on various anodized Ti-metal substrates by a RF magnetron sputtering method

Visible light-responsive TiO2 (Vis-TiO2) thin film has been deposited on two different kinds of anodized Ti-metal substrates, i.e., plate-type Titanystar (P-Titanystar) or non-woven fabric Titanystar (N-Titanystar) by a radio-frequency magnetron sputtering (RF-MS) method. These Vis-TiO2 thin film photocatalysts (Vis-TiO2/P-Titanystar and Vis-TiO2/N-Titanystar) showed high activity for the oxidation of 2-propanol in water under UV light irradiation while Vis-TiO2/N-Titanystar showed higher activity than Vis-TiO2/P-Titanystar. Furthermore, photocatalytic activity of Vis-TiO2/N-Titanystar was enhanced by the Pt deposition by an RF-MS deposition method. Pt loaded Vis-TiO2/N-Titanystar (Pt-Vis-TiO2/N-Titanystar) acted as an efficient photocatalyst for the oxidation of methanol vapor under UV light irradiation even in a flow system. Moreover, it was found that Pt-Vis-TiO2/N-Titanystar is an effective photocatalyst for the oxidation of various organic compounds in gas phase or ammonia gas even under visible light irradiation (λ > 420 nm) at 293 K.

Preparation of the visible light responsive TiO2 thin film photocatalysts by the RF magnetron sputtering deposition method

TiO2 thin film photocatalysts which could induce photoreactions under visible light irradiation were successfully developed in a single process by applying an ion engineering technique, i.e., the radio frequency (RF) magnetron sputtering deposition method. The TiO2 thin films prepared at temperatures greater than 773 K showed the efficient absorption of visible light; on the other hand, the TiO2 thin films prepared at around 573 K were highly transparent. This clearly means that the optical properties of TiO2 thin films, which absorb not only UV but also visible light, can be controlled by the preparation temperatures of the RF magnetron sputtering deposition method. These visible light responsive TiO2 thin films were found to exhibit effective photocatalytic reactivity under visible light irradiation (λ > 450 nm) at 275 K for the reductive decomposition of NO into N2 and N2O. From various characterizations, the orderly aligned columnar TiO2 crystals could be observed only for the visible light responsive TiO2 thin films. This unique structural factor is expected to modify the electronic properties of a TiO2 semiconductor, enabling the efficient absorption of visible light.

Preparation of Visible Light-responsive TiO2 Thin Film Photocatalysts by an RF Magnetron Sputtering Deposition Method and Their Photocatalytic Reactivity

Abstract Visible light-responsive TiO2 (Vis-TiO2) thin films were successfully developed by a radio-frequency (RF) magnetron sputtering deposition method. These Vis-TiO2 thin films exhibited a declined composition of the O/Ti ratio from the surface (O/Ti = 2.00) to bottom (O/Ti = 1.93), enabling the absorption of visible light. Pt-loaded Vis-TiO2 was, thus, found to decompose water involving methanol or a 0.05 M silver nitrate solution under visible light irradiation.