Introducing dual excitation and tunable dual emission in ZnO through selective lanthanide (Er3+/Ho3+) doping

Abstract

We have introduced dual excitation properties in the multifunctional semiconductor ZnO by controlled solid state diffusion of dopant lanthanide ions like Er³⁺ and Ho³⁺ into the lattice at 500 °C. So far light emission from doped ZnO has been explored either under UV or IR excitation. Our results show that the emission colour can be tuned from cyan to red under UV (band edge, 377 nm) excitation and from green to red under IR (980 nm) excitation in ZnO through selected doping of lanthanide ions. Doping lanthanide ions in ZnO changes its morphology and emission characteristics. Whereas down conversion emission under UV excitation is due to across band gap excitation and subsequent donor–acceptor pair recombination, the dependence of up conversion emission yield on pump laser power indicates that two to three photon processes may be more effective in ZnO hosts for frequency upconversion.