Probing of local alloy disorder in InGaN using Er³⁺ ions

We report on studies to probe the local lattice disorder in InGaN:Er epilayers using the 1.54 μm emission of Er³⁺ ions. The InGaN layers were doped during MOCVD growth with Er to a concentration of about 2.3%. Site selective optical spectroscopy and excitation photoluminescence spectroscopy were used to show that in InGaN:Er two classes of the emitting Er centers can be distinguished: (i) one leading to emission of Er³⁺ which is nearly the same as in GaN:Er, except nonuniform broadening and (ii) another that yields new emission features not having its counterpart in GaN:Er. The latter emission is interpreted as originating from Er-complexes involving one or more In atoms in the second coordination sphere. The observed fluorescence line broadening and wavelength shifts in the emission wavelength indicate the extent of the disorder in the metallic sublattice.