Slow luminescence from Er³⁺ centers in Er-Doped GeGaSe chalcogenide glasses observed by wideband quadrature frequency-resolved spectroscopy

Abstract

Wideband QFRS from 2 ns to 160 s of photoluminescence (PL) from Er-doped GeGaSe glasses reveals a PL component peaked at a slow lifetime τ_H ≈ 16 s at temperatures 3.7 and 294 K besides the prominent Er³⁺ emission peak at τ_Er ≈ 3.3 ms. The τ_H component has sharp PL peaks at photon energies ∼0.8 and ∼1.3 eV. On the other hand, the QFRS spectrum of the undoped sample has three peaks at 3.7 K; the first two peaks at ∼20 ns and ∼90 μs are associated with singlet and triplet excitons, and the slowest peak has a lifetime τ_H ≈ 16 s similar to that observed in the Er-doped sample. IR-induced quenching of the slow components of both the undoped and doped samples has been observed, suggesting a type of slow emission related to tunneling between tail-trapped photocarriers and D⁰ centers. The experimental results suggest also that the defect-related Auger effect probably mediates the energy transfer from precursors to Er³⁺ centers.