Photoluminescence Properties of Europium and Cerium Co-Doped Tantalum-Oxide Thin Films Prepared Using Co-Sputtering Method

Abstract

We fabricated europium and cerium co-doped tantalum (V) oxide (Ta 2 O 5 : Eu, Ce) thin films using our co-sputtering method for the first time, and evaluated photoluminescence (PL) properties of the films after annealing at 600 ° C - 1100 ° C for 20 min. Four remarkable PL peaks at wavelengths of 600, 620, 700, and 705 nm were observed from the film annealed at 900 ° C. The intensities of the 700- and 705-nm peaks due to the 5 D 0 → 7 F 4 transition of Eu 3+ were much stronger than those of the 600-nm ( 5 D 0 → 7 F 1 ) and 620-nm ( 5 D 0 → 7 F 2 ) peaks of the film annealed at 900 ° C. It seems that energy transfer from Ce 3+ to Eu 3+ occurs in the film, and much energy is selectively used for the 5 D 0 → 7 F 4 and 5 D 0 → 7 F 1 transitions. Such a Ta 2 O 5 : Eu, Ce co-sputtered thin film seems to be used as a multi-functional coating film having both anti-reflection and down-conversion effects for realizing a high-efficiency silicon solar cell.