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

Abstract

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.

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

“…We observed PL spectra having sharp peaks at a wavelength of 980 nm from the Ta 2 O 5 :Yb thin films after annealing at 700˚C to 1000˚C [7]. The 980-nm peaks seemed to be the result of the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ [7].…”

“…The energies of 4 S 3/2 (the origin of the 550-nm peak), 4 F 9/2 (the origin of the 670-nm peak), and 4 I 9/2 (the origin of the 850-nm peak) states of Er 3+ seem to transfer through the 4 I 11/2 state of Er 3+ to the 2 F 5/2 state of Yb 3+ as presented in Figure 3. [7]. The 980-nm peak from the Ta 2 O 5 :Yb film is much stronger than that from the Ta 2 O 5 :Er, Yb film.…”

“…[15]. The 980-nm peaks seem to be the results of the 4 I 11/2 → 4 I 15/2 transition of Er 3+ or the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ [7] [14]- [16]. From Figure 2, we can find that the 550-, 670-, and 850-nm peaks from the Ta 2 O 5 :Er film decreased by Yb doping.…”

“…Recently, we also fabricated ytterbium-doped Ta 2 O 5 (Ta 2 O 5 :Yb) thin films using the same co-sputtering method in order to expand the useful wavelength range of our rare-earth-doped and light-emitting Ta 2 O 5 co-sputtered films [7]. We observed PL spectra having sharp peaks at a wavelength of 980 nm from the Ta 2 O 5 :Yb thin films after annealing at 700˚C to 1000˚C [7]. The 980-nm peaks seemed to be the result of the 2 F 5/2 → 2 F 7/2 transition of Yb 3+ [7].…”

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

“…SiO 2 ) [6]. We have so far fabricated various rare-earth (Er [7]- [11], Tm [12] [13], Y [14], Yb [10] [15]. Such Ta 2 O 5 -based thin films seem to be used as high-refractive-index and light-emitting materials of "autocloning" photonic crystals that can be applied to novel light-emission devices [1], and they also seem to be used as multi-functional coating films having both anti-reflection [3] and downconversion [16]- [18] effects for realizing high-efficiency silicon solar cells.…”