Simple Co-sputtering Method Research Articles

High throughput preparation of Ni–Mo alloy thin films as efficient bifunctional electrocatalysts for water splitting

The synthesis of cost-effective and high-performance electrocatalysts for water splitting is the main challenge in electrochemical hydrogen production. In this study, we adopted a high throughput method to prepare bi-metallic catalysts for oxygen/hydrogen evolution reactions (OER/HER). A series of Ni–Mo alloy electrocatalysts with tunable compositions were prepared by a simple co-sputtering method. Due to the synergistic effect between Ni and Mo, the intrinsic electrocatalytic activity of the Ni–Mo alloy electrocatalysts is improved, resulting in excellent HER and OER performances. The Ni90Mo10 electrocatalyst shows the best HER performance, with an extremely low overpotential of 58 mV at 10 mA cm−2, while the Ni40Mo60 electrocatalyst shows an overpotential of 258 mV at 10 mA cm−2 in OER. More significantly, the assembled Ni40Mo60//Ni90Mo10 electrolyzer only needs a cell voltage of 1.57 V to reach 10 mA cm−2 for overall water splitting.

Photoluminescence Properties of Yb and Ag Co-Doped Ta<sub>2</sub>O<sub>5</sub> Thin Films

We prepared ytterbium and silver co-doped tantalum-oxide (Ta2O5:Yb,Ag) thin films using a simple co-sputtering method and evaluated photoluminescence (PL) properties of the films after annealing. We found that a PL peak at a wavelength of 980 nm due to Yb3+ can be strongly enhanced by Ag doping. From X-ray diffraction measurements, we found that Ag2Ta8O21 and orthorhombic Ta2O5 crystalline phases are very important in order to enhance the 980-nm peak observed from our Ta2O5:Yb,Ag thin films. Because of the human-body transmittability of the 980-nm wavelength, such films are applicable to a novel real-time X-ray dosimeter system.

Photoluminescence and X-Ray Diffraction Properties of Europium and Silver Co-Doped Tantalum-Oxide Thin Films Deposited by Co-Sputtering

We fabricated europium and silver co-doped tantalum-oxide (Ta2O5:Eu, Ag) thin films using a simple co-sputtering method for the first time, and we evaluated their photoluminescence (PL) and X-ray diffraction (XRD) properties. We found that the most remarkable PL peak at a wavelength of 615 nm due to Eu3+ can be enhanced by Ag doping, and the strongest PL peak can be obtained from a Ta2O5:Eu, Ag thin film after annealing at 1000℃. Based on XRD measurements, we found that Ag2Ta8O21 crystalline phases produced by Ag doping are very important and Eu3TaO7 phases should be avoided in order to enhance the objective PL peak from our Ta2O5:Eu, Ag thin films.

Observation of Blue-Light Emission Band from Eu-Doped Ta<sub>2</sub>O<sub>5 </sub>Thin Films Prepared Using Co-Sputtering

In this paper, we report on the first observation of blue-light emission bands from europium-doped tantalum pentoxide (Ta2O5:Eu) thin films prepared using a simple co-sputtering method. We prepared four specimens from one as-deposited sample, and we subsequently annealed them at 700&degC, 800&degC, 900&degC, or 1000&degC for 20 min. Four remarkable photoluminescence (PL) peaks at wavelengths of 600, 620, 650, and 700 nm due to the 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transitions of Eu3+ were observed from all the specimens, and blue PL peaks around a wavelength of 450 nm were also observed from the specimens annealed at 800&degC, 900&degC, and 1000&degC. The blue PL peaks seem to be originated from the 4f65d1→4f7 transition of Eu2+. Both Eu3+ and Eu2+ ions seem to exist in our Ta2O5:Eu co-sputtered thin films annealed at temperatures from 800&degC to 1000&degC. Such Ta2O5:Eu co-sputtered thin films seem to be used as multi-functional coating films having both anti-reflection and down-conversion effects for realizing high-efficiency silicon solar cells.

Preparation of Cr2O3-Ta2O5 Composites Using RF Magnetron Sputtering

We prepared Cr2O3-Ta2O5 composite films using our RF magnetron co-sputtering method for the first time. X-ray diffraction (XRD) patterns and photoluminescence (PL) spectra of the films annealed at 700℃, 800℃, 900℃, and 1000℃ were evaluated. From their XRD patterns, the Cr2O3-Ta2O5 film annealed at 700℃ seemed to be almost amorphous, and the one annealed at 800℃ seemed to be hexagonal Ta2O5 doped with Cr. In addition, the Cr2O3-Ta2O5 films annealed at 900℃ and 1000℃ seemed to include tetragonal CrTaO4 phases. Furthermore, it seems that almost no defect exists in our Cr2O3-Ta2O5 composite films annealed at 700℃ - 1000℃ because their PL spectra have no defect-related peak. We thus find that good-quality Cr2O3-Ta2O5 composite films including CrTaO4 can be obtained using our very simple co-sputtering method and subsequent annealing above 900℃.

Preparation of CuO-Ta<SUB>2</SUB>O<SUB>5</SUB> Composites Using a Simple Co-Sputtering Method

We prepared CuO-Ta2O5 composite films using our simple co-sputtering method for the first time. Four specimens were prepared from an as-deposited CuO-Ta2O5 sample by cutting it using a diamond- wire saw, and the specimens were subsequently annealed at 600°C - 900°C. The X-ray diffraction and photoluminescence (PL) of the annealed specimens were evaluated. The CuO-Ta2O5 film annealed at 600°C seemed to be primarily amorphous phase, and a sharp PL peak at a wavelength of 450 nm, due to the existence of Cu2+, was observed from the film. In contrast, the CuO-Ta2O5 films annealed at 700°C, 800°C, and 900°C seemed to be tetragonal CuTa2O6 phases. We expect that good-quality CuTa2O6 films can be obtained using our very simple co-sputtering method and subsequent annealing above 900°C. Such CuTa2O6 films can be used in chemisorptions conductometric gas sensors.

Photoluminescence and Crystalline Properties of CuO-Ta2O5 Composite Films Prepared Using Co-Sputtering

We prepared CuO-Ta2O5 composite films by our simple co-sputtering method using three CuO pellets and a Ta2O5 disc as a co-sputtering target, and subsequently annealed the films in ambient air at 900℃, 1000℃, and 1100℃ for 20 min. We evaluated photoluminesc...

Preparation of Light-Emitting Ytterbium-Doped Tantalum-Oxide Thin Films Using a Simple Co-Sputtering Method

Light-emitting ytterbium-doped tantalum-oxide thin films were prepared using a simple co-sputtering method for the first time. Sharp photoluminescence peaks having a wavelength of around 980 nm were observed from films annealed from 700&degC to 1000&degC for 10 to 40 min. The strongest intensity of the 980-nm peak was obtained from a film deposited using three ytterbium-oxide pellets and annealed at 800&degC for 20 min. Such rare-earth doped tantalum-oxide sputtered films can be used as high-refractive-index materials of autocloned photonic crystals that can be applied to novel light-emitting devices, and they will also be used as both anti-reflection and down-conversion layers for realizing high-efficiency silicon solar cells.

Fabrication of Erbium and Ytterbium Co-Doped Tantalum-Oxide Thin Films Using Radio-Frequency Co-Sputtering

An erbium and ytterbium co-doped tantalum-oxide (Ta2 O5:Er, Yb) thin film was fabricated using a simple co-sputtering method for the first time, and its photoluminescence (PL) spectrum was evaluated. Energy transfers between Er3+ and Yb3+ in the Ta2 O5:Er, Yb co-sputtered thin film were discussed by comparing between PL spectra of the Ta2 O5:Er, Yb film and Ta2 O5:Er or Ta2 O5:Yb films reported in our previous works. Such a Ta2 O5:Er, Yb co-sputtered film can be used as a high-refractive- index and light-emitting material of a multilayered photonic crystal that can be applied to a novel light-emitting device, and it will also be used as a multi-functional coating film having both anti-reflection and down-conversion effects for realizing a high-efficiency silicon solar cell.

Yellow light emission from Ta2O5:Er, Eu, Ce thin films deposited using a simple co-sputtering method

Erbium, europium, and cerium co-doped tantalum oxide (Ta2O5:Er, Eu, Ce) thin films were prepared using a simple co-sputtering method, and yellow light emission was observed by the naked eye from a sample annealed at 900°C for 20min. The hexagonal Ta2O5 phase is very important, but the hexagonal CeTa7O19 phase should be avoided to obtain strong yellow light emission from Ta2O5:Er, Eu, Ce films. The co-sputtered films can be used as high-refractive-index and yellow-light-emitting materials of autocloned photonic crystals that can be applied to novel light-emission devices, and they will also be used as anti-reflection and down-conversion layers toward high-efficiency silicon solar cells.

Fabrication of Tm-doped Ta2O5 thin films using a co-sputtering method

Thulium-doped tantalum-oxide (Ta2O5:Tm) thin films were prepared using a simple co-sputtering method. A remarkable photoluminescence peak having a wavelength of around 800nm due to Tm3+ was observed from a film annealed at 900°C for 20min. The δ-Ta2O5 (hexagonal) phase of the Ta2O5:Tm sputtered film is very important for obtaining strong photoluminescence.

Sputtered hydrogenated amorphous Si alloyed with Al

We have alloyed hydrogenated a-Si with Al, by a simple co-sputtering method. Up to Al concentrations of 23 at%, the material is a doped a-Si:H, and its resistivity decreases continuously down to the lowest value obtained to date for a-Si:H. As the Al concentration is increased above 23 at%, Al crystallization appears, accompanied by a non-monotonic behaviour of the resistivity.