Erbium-doped tantalum oxide films were prepared by radio-frequency magnetron sputtering. Visible light emission was observed from the films after annealing. We obtained PL peaks at 550 and 670 nm. The effects of erbium concentration, annealing temperature, and annealing time on the light-emitting properties of the films are discussed. The strongest intensities of the 550 and 670 nm peaks were observed from the samples with 0.96 and 0.63 mol% erbium concentrations after annealing at 900 • C for 20 min, respectively. Keywords: erbium, tantalum oxide, photoluminescence, annealing, sputtering Classification: Optoelectronics, Lasers and quantum electronics, Ultrafast optics, Silicon photonics, Planar lightwave circuits films," Opt. Mater., vol. 27, no. 12, pp. 1851-1858, Feb. 2005
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Thin films of Er-doped Ta2O5 have been synthesized by RF sputtering. The influence of annealing temperature, number of Er tablets and annealing time on the structural properties of grown films, has been studied. The samples annealed bellow 800°C show amorphous nature. However, the sample annealed at 800°C and above shows crystalline nature of the film with β–Ta2O5 (orthorhombic) and δ–Ta2O5 (hexagonal) phase. The crystalline structure of the film is disturbed with the increase in Er concentration.
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˚C to 1000˚C 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˚C 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.
The visible-light emission properties of erbium (Er)-doped tantalum-oxide films prepared by co-sputtering were evaluated. Photoluminescence (PL) peaks at wavelengths of 550 and 670 nm could be observed from these films by ultraviolet-laser excitation after annealing. The dependence of Er3+ concentration, annealing temperature, and annealing time on the PL peak intensities were investigated. Such light-emitting sputtered films can be useful as high-index materials of photonic crystals that can be applied to novel active devices.
An erbium and ytterbium co-doped tantalum-oxide (Ta2O5: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 Er 3+ and Yb 3+ in the Ta2O5:Er, Yb co-sputtered thin film were discussed by comparing between PL spectra of the Ta2O5:Er, Yb film and Ta2O5:Er or Ta2O5:Yb films reported in our previous works. Such a Ta2O5: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.
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