Photoluminescence Properties of Thulium and Cerium Co-Doped Tantalum-Oxide Films Prepared by Radio-Frequency Co-Sputtering

Abstract

We prepared thulium and cerium co-doped tantalum-oxide (Ta 2 O 5 :Tm, Ce) thin films by radiofrequency co-sputtering of Tm 2 O 3 and CeO 2 pellets on a Ta 2 O 5 disc for the first time, and photoluminescence (PL) properties of the films annealed at 700°C, 800 ° C, 900 ° C, or 1000 ° C for 20 min were evaluated. PL peaks around a wavelength of 800 nm due to Tm 3+ were observed for films annealed at 900 ° C or 1000 ° C. The peak intensities of films prepared using one Tm 2 O 3 pellet and one CeO 2 pellet were much stronger than those of films prepared using one Tm 2 O 3 pellet and two CeO 2 pellets or films prepared using two Tm 2 O 3 pellets and one CeO 2 pellet. To obtain the strongest PL intensity from the film, the proper Tm concentration was estimated to be around 1.0 mol%, and the proper Ce concentration was estimated to be around 1.3 mol%. Such Ta 2 O 5 :Tm, Ce co-sputtered thin 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 anti-reflection and downconversion layers for realizing high-efficiency silicon solar cells.