Red Photoluminescence from Fe-Doped MgAl₂O₄ Crystals

Abstract

The influence of variations in composition (x = MgO/Al2O3 = 0.3–1.0), Fe2O3 concentrations (0.05 mol%–2.0 mol%), and O2 concentrations (100 vol% and 0 vol%) in the atmosphere on the PL characteristics of Fe-doped MgAl2O4 crystals were investigated using single phase spinel crystals grown by FZ technique. The peak wavelength shift of photoluminescence at around 730 nm are observed depending on the Fe2O3 concentration and composition. Concentration quenching of red PL occurred at Fe2O3 concentration above 0.1 mol%. PL intensity was higher in samples grown in 100 vol% O2 compared to those grown in 100 vol% Ar. PL intensity from Fe-doped MgAl2O4 increased with increasing compositions x from 0.3 to 1.0. MgAl2O4 doped with 0.1 mol% Fe2O3, and a stoichiometric composition (x = 1.0) grown in 100 vol% O2, demonstrated strong red PL with ultraviolet-C (UVC) lights excitation.