Room temperature cathodoluminescence quenching of Er³⁺ in AlNOEr

This paper reports a cathodoluminescence (CL) spectroscopic study of nanogranular AlNOEr _x samples with erbium content, x, in the range 0.5–3.6 at%. A wide range of erbium concentration was studied with the aim of understanding the concentration quenching of CL. The composition of thin films, deposited by radiofrequency reactive magnetron sputtering, was accurately determined by Energy Dispersive X-ray Spectroscopy (EDS). CL emission was investigated in the extended visible spectral range from 350 nm to 850 nm. The critical concentration of luminescent activator Er ³⁺ above which CL quenching occurs is 1%; the corresponding critical distance between Er ³⁺ ions in AlNOEr _x is about 1.0 nm. The quenching mechanism is discussed. We discount an exchange-mediated interaction in favour of a multipole-multipole phonon-assisted interaction.