Solution-processed Er3+-doped As3S7 chalcogenide films: optical properties and 1.5 μm photoluminescence activated by thermal treatment

Abstract

We report on the optical properties of Er-doped As₃S₇ chalcogenide films prepared using the two step dissolution process utilizing the As₃S₇ glass dissolved with propylamine and by further addition of the tris(8-hydroxyquinolinato)erbium(III) (ErQ) complex acting as an Er³⁺ precursor. Thin films were deposited by spin-coating, thermally stabilized by annealing at 125 °C and further post-annealed at 200 or 300 °C. The post-annealing of films at 200 °C and 300 °C densifies the films, improves their optical homogeneity, and moreover activates the Er³⁺:⁴I_13/2 → ⁴I_15/2 (λ ≈ 1.5 μm) PL emission at pumping wavelengths of 808 and 980 nm. The highest PL emission intensity was achieved for As₃S₇ films post-annealed at 300 °C and doped with ≈1 at% of Er which is beyond the normal Er³⁺ solubility limit of As–S melt-quenched glasses. The solution-processed deposition of the rare-earth-doped chalcogenide films utilizing the organolanthanide precursors has much potential for application in printed flexible optoelectronics and photonics.